Merge from gnulib for 'inline', incorporating:

2012-12-11 extern-inline: avoid incompatibility with Darwin Libc
* m4/extern-inline.m4: Update from gnulib.

Fixes: debbugs:13040

ChangeLog

+2012-12-11  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Merge from gnulib for 'inline' (Bug#13040), incorporating:
+	2012-12-11 extern-inline: avoid incompatibility with Darwin Libc
+	* m4/extern-inline.m4: Update from gnulib.
+
 2012-12-11  Juanma Barranquero  <lekktu@gmail.com>
 
 	* lib/makefile.w32-in (SIG2STR_H): New macro.

m4/extern-inline.m4

@@ -16,13 +16,19 @@ AC_DEFUN([gl_EXTERN_INLINE],
      when FOO is an inline function in the header; see
      <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113>.
    _GL_INLINE_HEADER_END contains useful stuff to put
-     in the same include file, after uses of _GL_INLINE.  */
-#if (__GNUC__ \
-     ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
-     : 199901L <= __STDC_VERSION__)
+     in the same include file, after uses of _GL_INLINE.
+
+   Suppress the use of extern inline on Apple's platforms,
+   as Libc-825.25 (2012-09-19) is incompatible with it; see
+   <http://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00023.html>.
+   Perhaps Apple will fix this some day.  */
+#if ((__GNUC__ \
+      ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
+      : 199901L <= __STDC_VERSION__) \
+     && !defined __APPLE__)
 # define _GL_INLINE inline
 # define _GL_EXTERN_INLINE extern inline
-#elif 2 < __GNUC__ + (7 <= __GNUC_MINOR__)
+#elif 2 < __GNUC__ + (7 <= __GNUC_MINOR__) && !defined __APPLE__
 # if __GNUC_GNU_INLINE__
    /* __gnu_inline__ suppresses a GCC 4.2 diagnostic.  */
 #  define _GL_INLINE extern inline __attribute__ ((__gnu_inline__))
@@ -31,8 +37,8 @@ AC_DEFUN([gl_EXTERN_INLINE],
 # endif
 # define _GL_EXTERN_INLINE extern
 #else
-# define _GL_INLINE static
-# define _GL_EXTERN_INLINE static
+# define _GL_INLINE static _GL_UNUSED
+# define _GL_EXTERN_INLINE static _GL_UNUSED
 #endif
 
 #if 4 < __GNUC__ + (6 <= __GNUC_MINOR__)