Merge from gnulib

This incorporates:
2013-03-29 stdalign: port to stricter ISO C11
This helps to run 'configure' on MS-Windows; see Eli Zaretskii in
<http://lists.gnu.org/archive/html/emacs-devel/2013-03/msg00999.html>.

ChangeLog

+2013-03-30  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Merge from gnulib, incorporating:
+	2013-03-29 stdalign: port to stricter ISO C11
+	This helps to run 'configure' on MS-Windows; see Eli Zaretskii in
+	<http://lists.gnu.org/archive/html/emacs-devel/2013-03/msg00999.html>.
+
 2013-03-27  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* configure.ac (HAVE_XKBGETKEYBOARD): Remove.

m4/stdalign.m4

@@ -33,8 +33,9 @@ AC_DEFUN([gl_STDALIGN_H],
             #if \
                 (__GNUC__ || __IBMC__ || __IBMCPP__ \
                  || 0x5110 <= __SUNPRO_C || 1300 <= _MSC_VER)
-              int alignas (8) alignas_int = 1;
-              char test_alignas[_Alignof (alignas_int) == 8 ? 1 : -1];
+              struct alignas_test { char c; char alignas (8) alignas_8; };
+              char test_alignas[offsetof (struct alignas_test, alignas_8) == 8
+                                ? 1 : -1];
             #endif
           ]])],
        [gl_cv_header_working_stdalign_h=yes],