Fix crash on VirtualBox (and probably on some real hardware):

- Do not cover error returned by pmc_core_initialize with the
    result of pmc_uncore_initialize, fail right away.
- Give a user something to report instead failing silently

Reported by:	Alexandr Kovalenko <never@nevermind.kiev.ua>

sys/dev/hwpmc/hwpmc_core.c

@@ -2406,8 +2406,12 @@ pmc_core_initialize(struct pmc_mdep *md, int maxcpu)
 	PMCDBG(MDP,INI,1,"core-init cputype=%d ncpu=%d ipa-version=%d",
 	    md->pmd_cputype, maxcpu, ipa_version);
 
-	if (ipa_version < 1 || ipa_version > 3)	/* Unknown PMC architecture. */
+	if (ipa_version < 1 || ipa_version > 3) {
+		/* Unknown PMC architecture. */
+		printf("hwpc_core: unknown PMC architecture: %d\n",
+		    ipa_version);
 		return (EPROGMISMATCH);
+	}
 
 	core_cputype = md->pmd_cputype;
 

sys/dev/hwpmc/hwpmc_intel.c

@@ -239,6 +239,9 @@ pmc_intel_initialize(void)
 		KASSERT(0, ("[intel,%d] Unknown CPU type", __LINE__));
 	}
 
+	if (error)
+		goto error;
+
 	/*
 	 * Init the uncore class.
 	 */