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

1 files changed, 22 insertions, 17 deletions

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
 ])