Update from gnulib

(cherry picked from commit 992cf3cb67)

This is a partial backport from master: it only includes the changes below.

* lib/mini-gmp.c (gmp_assert_nocarry): Avoid many Clang
unused-variable warnings when building with optimisation.
* lib/verify.h (_GL_HAVE__STATIC_ASSERT): Modify condition for using
_Static_assert to cope with older Apple builds of Clang exposing
misleading compiler version numbers.  See discussion starting at
https://lists.gnu.org/archive/html/emacs-devel/2022-04/msg00779.html

lib/mini-gmp.c

@@ -90,6 +90,7 @@ see https://www.gnu.org/licenses/.  */
 #define gmp_assert_nocarry(x) do { \
     mp_limb_t __cy = (x);	   \
     assert (__cy == 0);		   \
+    (void) (__cy);		   \
   } while (0)
 
 #define gmp_clz(count, x) do {						\

lib/verify.h

@@ -34,7 +34,7 @@
 #ifndef __cplusplus
 # if (201112L <= __STDC_VERSION__ \
       || (!defined __STRICT_ANSI__ \
-          && (4 < __GNUC__ + (6 <= __GNUC_MINOR__) || 4 <= __clang_major__)))
+          && (4 < __GNUC__ + (6 <= __GNUC_MINOR__) || 5 <= __clang_major__)))
 #  define _GL_HAVE__STATIC_ASSERT 1
 # endif
 # if (202000L <= __STDC_VERSION__ \