Propagate unlikely executed BBs even on measured profiles

Propagate unlikely executed BBs even on measured profiles

While looking into AutoFDO porfiles I noticed that sometimes we lost
precise zero counts due to inlining and merging basic blocks.  Propagating
precise zero counts should be safe even for measured profiles and thus
this patch enables it.

gcc/ChangeLog:

	* predict.cc (unlikely_executed_stmt_p): Remove redundant check.
	(rebuild_frequencies): Also recompute unlikely bbs when profile is
	present or consistent.