Don't substitute sigprocmask for pthread_sigmask.

sigprocmask isn't portable in a multithreaded process.
* configure.ac (gl_THREADLIB): Remove dummy.
Merge from gnulib, incorporating:
2014-05-28 pthread_sigmask, timer-time: use gl_THREADLIB only if needed
* m4/pthread_sigmask.m4, m4/timer_time.m4: Update from gnulib.
* src/Makefile.in (LIB_PTHREAD_SIGMASK): Remove; all uses removed.

Fixes: debbugs:17561

2 files changed, 67 insertions, 57 deletions

diff --git a/m4/pthread_sigmask.m4 b/m4/pthread_sigmask.m4
index 4ba073231f9..2b3347f992d 100644
--- a/m4/pthread_sigmask.m4
+++ b/m4/pthread_sigmask.m4
@@ -1,4 +1,4 @@
-# pthread_sigmask.m4 serial 13
+# pthread_sigmask.m4 serial 14
 dnl Copyright (C) 2011-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -97,39 +97,43 @@ AC_DEFUN([gl_FUNC_PTHREAD_SIGMASK],
     dnl with -lpthread, the pthread_sigmask() function always returns 0 and has
     dnl no effect.
     if test -z "$LIB_PTHREAD_SIGMASK"; then
-      AC_CACHE_CHECK([whether pthread_sigmask works without -lpthread],
-        [gl_cv_func_pthread_sigmask_in_libc_works],
-        [
-          AC_RUN_IFELSE(
-            [AC_LANG_SOURCE([[
-#include <pthread.h>
-#include <signal.h>
-#include <stddef.h>
-int main ()
-{
-  sigset_t set;
-  sigemptyset (&set);
-  return pthread_sigmask (1729, &set, NULL) != 0;
-}]])],
-            [gl_cv_func_pthread_sigmask_in_libc_works=no],
-            [gl_cv_func_pthread_sigmask_in_libc_works=yes],
-            [
-changequote(,)dnl
-             case "$host_os" in
-               freebsd* | hpux* | solaris | solaris2.[2-9]*)
-                 gl_cv_func_pthread_sigmask_in_libc_works="guessing no";;
-               *)
-                 gl_cv_func_pthread_sigmask_in_libc_works="guessing yes";;
-             esac
-changequote([,])dnl
-            ])
-        ])
-      case "$gl_cv_func_pthread_sigmask_in_libc_works" in
-        *no)
-          REPLACE_PTHREAD_SIGMASK=1
-          AC_DEFINE([PTHREAD_SIGMASK_INEFFECTIVE], [1],
-            [Define to 1 if pthread_sigmask() may returns 0 and have no effect.])
-          ;;
+      case " $LIBS " in
+        *' -lpthread '*) ;;
+        *)
+          AC_CACHE_CHECK([whether pthread_sigmask works without -lpthread],
+            [gl_cv_func_pthread_sigmask_in_libc_works],
+            [
+              AC_RUN_IFELSE(
+                [AC_LANG_SOURCE([[
+                   #include <pthread.h>
+                   #include <signal.h>
+                   #include <stddef.h>
+                   int main ()
+                   {
+                     sigset_t set;
+                     sigemptyset (&set);
+                     return pthread_sigmask (1729, &set, NULL) != 0;
+                   }]])],
+                [gl_cv_func_pthread_sigmask_in_libc_works=no],
+                [gl_cv_func_pthread_sigmask_in_libc_works=yes],
+                [
+                 changequote(,)dnl
+                 case "$host_os" in
+                   freebsd* | hpux* | solaris | solaris2.[2-9]*)
+                     gl_cv_func_pthread_sigmask_in_libc_works="guessing no";;
+                   *)
+                     gl_cv_func_pthread_sigmask_in_libc_works="guessing yes";;
+                 esac
+                 changequote([,])dnl
+                ])
+            ])
+          case "$gl_cv_func_pthread_sigmask_in_libc_works" in
+            *no)
+              REPLACE_PTHREAD_SIGMASK=1
+              AC_DEFINE([PTHREAD_SIGMASK_INEFFECTIVE], [1],
+                [Define to 1 if pthread_sigmask may return 0 and have no effect.])
+              ;;
+          esac;;
       esac
     fi
 
@@ -184,11 +188,12 @@ int main ()
           *)
             gl_cv_func_pthread_sigmask_unblock_works="guessing yes";;
         esac
-        dnl Here we link against $LIBMULTITHREAD, not only $LIB_PTHREAD_SIGMASK,
-        dnl otherwise we get a false positive on those platforms where
-        dnl $gl_cv_func_pthread_sigmask_in_libc_works is "no".
-        gl_save_LIBS="$LIBS"
-        LIBS="$LIBS $LIBMULTITHREAD"
+        m4_ifdef([gl_][THREADLIB],
+          [dnl Link against $LIBMULTITHREAD, not only $LIB_PTHREAD_SIGMASK.
+           dnl Otherwise we get a false positive on those platforms where
+           dnl $gl_cv_func_pthread_sigmask_in_libc_works is "no".
+           gl_save_LIBS=$LIBS
+           LIBS="$LIBS $LIBMULTITHREAD"])
         AC_RUN_IFELSE(
           [AC_LANG_SOURCE([[
 #include <pthread.h>
@@ -227,7 +232,7 @@ int main ()
           [:],
           [gl_cv_func_pthread_sigmask_unblock_works=no],
           [:])
-        LIBS="$gl_save_LIBS"
+        m4_ifdef([gl_][THREADLIB], [LIBS=$gl_save_LIBS])
       ])
     case "$gl_cv_func_pthread_sigmask_unblock_works" in
       *no)
diff --git a/m4/timer_time.m4 b/m4/timer_time.m4
index 8e2c921cbef..578ebe0809a 100644
--- a/m4/timer_time.m4
+++ b/m4/timer_time.m4
@@ -1,4 +1,4 @@
-# timer_time.m4 serial 2
+# timer_time.m4 serial 3
 dnl Copyright (C) 2011-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -11,7 +11,12 @@ AC_DEFUN([gl_TIMER_TIME],
   dnl Based on clock_time.m4. See details there.
 
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
-  AC_REQUIRE([gl_THREADLIB])
+
+  dnl Test whether the gnulib module 'threadlib' is in use.
+  dnl Some packages like Emacs use --avoid=threadlib.
+  dnl Write the symbol in such a way that it does not cause 'aclocal' to pick
+  dnl the threadlib.m4 file that is installed in $PREFIX/share/aclocal/.
+  m4_ifdef([gl_][THREADLIB], [AC_REQUIRE([gl_][THREADLIB])])
 
   LIB_TIMER_TIME=
   AC_SUBST([LIB_TIMER_TIME])
@@ -19,21 +24,21 @@ AC_DEFUN([gl_TIMER_TIME],
     AC_SEARCH_LIBS([timer_settime], [rt posix4],
                    [test "$ac_cv_search_timer_settime" = "none required" ||
                     LIB_TIMER_TIME=$ac_cv_search_timer_settime])
-    dnl GLIBC uses threads to emulate posix timers when kernel support
-    dnl is not available (like Linux < 2.6 or when used with kFreeBSD)
-    dnl Now the pthread lib is linked automatically in the normal case,
-    dnl but when linking statically, it needs to be explicitly specified.
-    AC_EGREP_CPP([Thread],
-      [
-#include <features.h>
-#ifdef __GNU_LIBRARY__
- #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2) || (__GLIBC__ > 2)) \
-     && !(__UCLIBC__ && __HAS_NO_THREADS__)
-  Thread emulation available
- #endif
-#endif
-      ],
-      [LIB_TIMER_TIME="$LIB_TIMER_TIME $LIBMULTITHREAD"])
+    m4_ifdef([gl_][THREADLIB],
+      [dnl GLIBC uses threads to emulate posix timers when kernel support
+       dnl is not available (like Linux < 2.6 or when used with kFreeBSD)
+       dnl Now the pthread lib is linked automatically in the normal case,
+       dnl but when linking statically, it needs to be explicitly specified.
+       AC_EGREP_CPP([Thread],
+         [#include <features.h>
+          #ifdef __GNU_LIBRARY__
+           #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2) || (__GLIBC__ > 2)) \
+               && !(__UCLIBC__ && __HAS_NO_THREADS__)
+            Thread emulation available
+           #endif
+          #endif
+         ],
+         [LIB_TIMER_TIME="$LIB_TIMER_TIME $LIBMULTITHREAD"])])
     AC_CHECK_FUNCS([timer_settime])
   LIBS=$gl_saved_libs
 ])