scan generic vector tests before lowering

scan generic vector tests before lowering

The g++.dg/pr94920.C testcase looks for a specific number of
ABS_EXPRs but the vector example is prone to vector lowering so
the following instead of scanning the optimized dump scans the
forwprop1 dump which is before vector lowering and the point the
transforms should have happened.

	* g++.dg/pr94920.C: Scan forwprop1 instead of optimized.