kselftest/arm64: signal: Skip tests if required features are missing

During initialization of a signal testcase, features declared as required
are properly checked against the running system but no action is then taken
to effectively skip such a testcase.

Fix core signals test logic to abort initialization and report such a
testcase as skipped to the KSelfTest framework.

Fixes: f96bf4340316 ("kselftest: arm64: mangle_pstate_invalid_compat_toggle and common utils")
Signed-off-by: Cristian Marussi <[e-mail]>
Reviewed-by: Mark Brown <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Catalin Marinas <[e-mail]>

tools/testing/selftests/arm64/signal/test_signals_utils.c

···
 			td->feats_supported |= FEAT_SSBS;
 		if (getauxval(AT_HWCAP) & HWCAP_SVE)
 			td->feats_supported |= FEAT_SVE;
-		if (feats_ok(td))
+		if (feats_ok(td)) {
 			fprintf(stderr,
 				"Required Features: [%s] supported\n",
 				feats_to_string(td->feats_required &
 						td->feats_supported));
-		else
+		} else {
 			fprintf(stderr,
 				"Required Features: [%s] NOT supported\n",
 				feats_to_string(td->feats_required &
 						~td->feats_supported));
+			td->result = KSFT_SKIP;
+			return 0;
+		}
 	}
 
 	/* Perform test specific additional initialization */