memrchr tests: Avoid GCC warning

[Bruno Haible]

Compiling a current grep snapshot with GCC 4.5.4, I see this warning:

  CC       test-memrchr.o
../../gnulib-tests/test-memrchr.c:32:10: warning: unknown option after '#pragma 
GCC diagnostic' kind

The reason is that '#pragma GCC diagnostic' is only supported for
GCC ≥ 4.7, see
<https://lists.gnu.org/archive/html/bug-gnulib/2023-03/msg00033.html>.

This patch should fix it.


2023-03-20  Bruno Haible  <bruno@clisp.org>

        memrchr tests: Avoid GCC warning.
        * tests/test-memrchr.c: Don't use '#pragma GCC diagnostic' for GCC
        versions older than 4.7.

diff --git a/tests/test-memrchr.c b/tests/test-memrchr.c
index 0fd22187ab..7c52e7ca2e 100644
--- a/tests/test-memrchr.c
+++ b/tests/test-memrchr.c
@@ -28,7 +28,7 @@ SIGNATURE_CHECK (memrchr, void *, (void const *, int, 
size_t));
 #include "macros.h"
 
 /* Work around GCC bug 101494.  */
-#if 4 < __GNUC__ + (3 <= __GNUC_MINOR__) && __GNUC__ < 12
+#if 4 < __GNUC__ + (7 <= __GNUC_MINOR__) && __GNUC__ < 12
 # pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
 #endif