selftests: exec: return Kselftest Skip code for skipped tests

When execveat test is skipped because of unmet dependencies and/or
unsupported configuration, it exits with error which is treated as
a fail by the Kselftest framework. This leads to false negative
result even when the test could not be run.

Change it to return kselftest skip code when a test gets skipped to
clearly report that the test could not be run.

Change it to use ksft_exit_skip() when kernel doesn't support execveat.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/exec/execveat.c

@@ -20,6 +20,8 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "../kselftest.h"
+
 static char longpath[2 * PATH_MAX] = "";
 static char *envp[] = { "IN_TEST=yes", NULL, NULL };
 static char *argv[] = { "execveat", "99", NULL };
@@ -249,8 +251,8 @@ static int run_tests(void)
 	errno = 0;
 	execveat_(-1, NULL, NULL, NULL, 0);
 	if (errno == ENOSYS) {
-		printf("[FAIL] ENOSYS calling execveat - no kernel support?\n");
-		return 1;
+		ksft_exit_skip(
+			"ENOSYS calling execveat - no kernel support?\n");
 	}
 
 	/* Change file position to confirm it doesn't affect anything */