Do not leak PMC_PO_OWNS_LOGFILE on error.

Note that PMCLOG_RESERVE_WITH_ERROR() macro contains goto error;
statement and executed after the flag is set.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

sys/dev/hwpmc/hwpmc_logging.c

@@ -683,6 +683,7 @@ pmclog_configure_log(struct pmc_mdep *md, struct pmc_owner *po, int logfd)
 		(void) fdrop(po->po_file, curthread);
 	po->po_file  = NULL;	/* clear file and error state */
 	po->po_error = 0;
+	po->po_flags &= ~PMC_PO_OWNS_LOGFILE;
 
 	return (error);
 }