selftests/nolibc: skip tests for unimplemented syscalls

The riscv32 architecture is missing many of the older syscalls.
Instead of providing wrappers for everything at once, introducing a lot
of complexity, skip the tests for those syscalls for now.

Link: https://lore.kernel.org/r/20241221-nolibc-rv32-v1-4-d9ef6dab7c63@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

tools/testing/selftests/nolibc/nolibc-test.c

@@ -302,7 +302,10 @@ int expect_syszr(int expr, int llen)
 {
 	int ret = 0;
 
-	if (expr) {
+	if (errno == ENOSYS) {
+		llen += printf(" = ENOSYS");
+		result(llen, SKIPPED);
+	} else if (expr) {
 		ret = 1;
 		llen += printf(" = %d %s ", expr, errorname(errno));
 		result(llen, FAIL);
@@ -342,7 +345,10 @@ int expect_sysne(int expr, int llen, int val)
 {
 	int ret = 0;
 
-	if (expr == val) {
+	if (errno == ENOSYS) {
+		llen += printf(" = ENOSYS");
+		result(llen, SKIPPED);
+	} else if (expr == val) {
 		ret = 1;
 		llen += printf(" = %d %s ", expr, errorname(errno));
 		result(llen, FAIL);
@@ -367,7 +373,9 @@ int expect_syserr2(int expr, int expret, int experr1, int experr2, int llen)
 	int _errno = errno;
 
 	llen += printf(" = %d %s ", expr, errorname(_errno));
-	if (expr != expret || (_errno != experr1 && _errno != experr2)) {
+	if (errno == ENOSYS) {
+		result(llen, SKIPPED);
+	} else if (expr != expret || (_errno != experr1 && _errno != experr2)) {
 		ret = 1;
 		if (experr2 == 0)
 			llen += printf(" != (%d %s) ", expret, errorname(experr1));