Update from Gnulib

This incorporates:
2020-05-09 stdio: don't redefine _GL_ATTRIBUTE_FORMAT
2020-05-09 dirent, stdlib, string: don't redefine _GL_ATTRIBUTE_PURE
2020-05-08 limits-h: define LONG_BIT correctly on Haiku/x86_64
2020-05-08 ignore-value tests: use module 'attribute'
2020-05-06 attribute: minor style fixes
* build-aux/config.sub, doc/misc/texinfo.tex, lib/attribute.h:
* lib/dirent.in.h, lib/limits.in.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/string.in.h, m4/gnulib-common.m4:
Copy from Gnulib.

1 files changed, 6 insertions, 4 deletions

diff --git a/lib/stdlib.in.h b/lib/stdlib.in.h
index ec5f124a366..59f9e6c71d1 100644
--- a/lib/stdlib.in.h
+++ b/lib/stdlib.in.h
@@ -101,10 +101,12 @@ struct random_data
 
 /* The __attribute__ feature is available in gcc versions 2.5 and later.
    The attribute __pure__ was added in gcc 2.96.  */
-#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
-# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
-#else
-# define _GL_ATTRIBUTE_PURE /* empty */
+#ifndef _GL_ATTRIBUTE_PURE
+# if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
+#  define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
+# else
+#  define _GL_ATTRIBUTE_PURE /* empty */
+# endif
 #endif
 
 /* The definition of _Noreturn is copied here.  */