Merge from gnulib, incorporating:

2013-11-13 getgroups: work around _DARWIN_C_SOURCE problem
* lib/getgroups.c: Update from gnulib.

ChangeLog

+2013-11-27  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Merge from gnulib, incorporating:
+	2013-11-13 getgroups: work around _DARWIN_C_SOURCE problem
+	* lib/getgroups.c: Update from gnulib.
+
 2013-11-27  Glenn Morris  <rgm@gnu.org>
 
 	Move ja-dic, quail, leim-list.el from leim to lisp/leim.

lib/getgroups.c

@@ -43,6 +43,21 @@ getgroups (int n _GL_UNUSED, GETGROUPS_T *groups _GL_UNUSED)
 #  define GETGROUPS_ZERO_BUG 0
 # endif
 
+/* On OS X 10.6 and later, use the usual getgroups, not the one
+   supplied when _DARWIN_C_SOURCE is defined.  _DARWIN_C_SOURCE is
+   normally defined, since it means "conform to POSIX, but add
+   non-POSIX extensions even if that violates the POSIX namespace
+   rules", which is what we normally want.  But with getgroups there
+   is an inconsistency, and _DARWIN_C_SOURCE means "change getgroups()
+   so that it no longer works right".  The BUGS section of compat(5)
+   says that the behavior is dubious if you compile different sections
+   of a program with different _DARWIN_C_SOURCE settings, so fix only
+   the offending symbol.  */
+# ifdef __APPLE__
+int posix_getgroups (int, gid_t []) __asm ("_getgroups");
+#  define getgroups posix_getgroups
+# endif
+
 /* On at least Ultrix 4.3 and NextStep 3.2, getgroups (0, NULL) always
    fails.  On other systems, it returns the number of supplemental
    groups for the process.  This function handles that special case