Fix gcc 9 build errors for make xcheck. [BZ #24556]

This patch fixes the following gcc 9 warnings for "make xcheck" / "make bench":
-string/tst-strcasestr.c:
../include/bits/../../misc/bits/error.h:42:5: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

-argp/argp-test.c:
argp-test.c:130:20: error: ‘%d’ directive writing between 1 and 11 bytes into a region of size 10 [-Werror=format-overflow=]
argp-test.c:130:19: note: directive argument in the range [-2147483648, 122]
argp-test.c:130:5: note: ‘sprintf’ output between 2 and 12 bytes into a destination of size 10

-nss/tst-field.c:
tst-field.c:52:7: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

-benchtests/bench-strstr.c:
../include/bits/../../misc/bits/error.h:42:5: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

-benchtests/bench-malloc-simple.c:
bench-malloc-simple.c:93:16: error: iteration 3 invokes undefined behavior [-Werror=aggressive-loop-optimizations]

ChangeLog:

	[BZ #24556]
	* string/test-strcasestr.c (check_result): Add NULL check.
	* nss/tst-field.c (check_rewrite): Likewise.
	* benchtests/bench-strstr.c (do_one_test): Likewise.
	* string/test-strstr.c (check_result): Likewise.
	* argp/argp-test.c (popt): Increase size of buf to 12.
	* benchtests/bench-malloc-simple.c (bench):
	Do not initialize tests array out of bounds.

1 files changed, 2 insertions, 1 deletions

diff --git a/nss/tst-field.c b/nss/tst-field.c
index 23d2f2a..d98d3ee 100644
--- a/nss/tst-field.c
+++ b/nss/tst-field.c
@@ -50,7 +50,8 @@ check_rewrite (const char *input, const char *expected)
   if (result != NULL && strcmp (result, expected) != 0)
     {
       printf ("FAIL: rewrite \"%s\" -> \"%s\", expected \"%s\"\n",
-	      input, result, expected);
+	      (input == NULL) ? "(null)" : input, result,
+	      (expected == NULL) ? "(null)" : expected);
       errors = true;
     }
   free (to_free);