selftests: capabilities: fix to run Non-root +ia, sgidroot => i test

do_tests() runs sgidnonroot test without fork_wait(). As a result the
last test "Non-root +ia, sgidroot => i test" is left out. Fix it.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/capabilities/test_execve.c

@@ -380,7 +380,8 @@ static int do_tests(int uid, const char *our_path)
 						true, true, true, false);
 	} else {
 		printf("[RUN]\tNon-root +ia, sgidnonroot => i\n");
-		exec_other_validate_cap("./validate_cap_sgidnonroot",
+		if (fork_wait())
+			exec_other_validate_cap("./validate_cap_sgidnonroot",
 					false, false, true, false);
 
 		if (fork_wait()) {