selftests: harness: Mark functions without prototypes static

With -Wmissing-prototypes the compiler will warn about non-static
functions which don't have a prototype defined.
As they are not used from a different compilation unit they don't need to
be defined globally.

Avoid the issue by marking the functions static.

Signed-off-by: Thomas Weißschuh <[email protected]>
Reviewed-by: Muhammad Usama Anjum <[email protected]>
Acked-by: Shuah Khan <[email protected]>
Link: https://lore.kernel.org/r/20250505-nolibc-kselftest-harness-v4-4-ee4dd5257135@linutronix.de
Signed-off-by: Thomas Weißschuh <[email protected]>

Author: t-8ch

tools/testing/selftests/kselftest_harness.h

@@ -258,7 +258,7 @@
  * A bare "return;" statement may be used to return early.
  */
 #define FIXTURE_SETUP(fixture_name) \
-	void fixture_name##_setup( \
+	static void fixture_name##_setup( \
 		struct __test_metadata __attribute__((unused)) *_metadata, \
 		FIXTURE_DATA(fixture_name) __attribute__((unused)) *self, \
 		const FIXTURE_VARIANT(fixture_name) \
@@ -307,7 +307,7 @@
 	__FIXTURE_TEARDOWN(fixture_name)
 
 #define __FIXTURE_TEARDOWN(fixture_name) \
-	void fixture_name##_teardown( \
+	static void fixture_name##_teardown( \
 		struct __test_metadata __attribute__((unused)) *_metadata, \
 		FIXTURE_DATA(fixture_name) __attribute__((unused)) *self, \
 		const FIXTURE_VARIANT(fixture_name) \
@@ -987,7 +987,7 @@ static void __timeout_handler(int sig, siginfo_t *info, void *ucontext)
 	kill(-(t->pid), SIGKILL);
 }
 
-void __wait_for_test(struct __test_metadata *t)
+static void __wait_for_test(struct __test_metadata *t)
 {
 	struct sigaction action = {
 		.sa_sigaction = __timeout_handler,
@@ -1205,9 +1205,9 @@ static bool test_enabled(int argc, char **argv,
 	return !has_positive;
 }
 
-void __run_test(struct __fixture_metadata *f,
-		struct __fixture_variant_metadata *variant,
-		struct __test_metadata *t)
+static void __run_test(struct __fixture_metadata *f,
+		       struct __fixture_variant_metadata *variant,
+		       struct __test_metadata *t)
 {
 	struct __test_xfail *xfail;
 	char test_name[1024];