Programming fails silently for counters with PMC restrictions

[travisdowns]

I finally figured out why l1d_pend_miss counters weren't working with libpfc. It's due to this code:

if((evtNum == 0x48) ||                                   /* l1d_pend_miss */
	   (evtNum == 0xA3 && (umask == 0x08 || umask == 0x0C))){/* cycle_activity.l1d_pending */
		if(i != 2){
			c = 0;/* Disable. */
		}
	}

It would be nice to get an error messages to the system log in that case, so we don't have to hunt around to understand what's going on.

I'll send a pull request for this.