forwprop: Move around the marking bb for eh to after the local non-fold_stmt optimiza...

forwprop: Move around the marking bb for eh to after the local non-fold_stmt optimizations

When moving the optimize_memcpy_to_memset optimization to forwprop from fold_stmt, the marking
of the bb to purge for eh cleanup was not happening for the local optimizations but only after
the fold_stmt, this causes g++.dg/torture/except-2.C to fail.
So this patch moves the marking of the bbs for cleanups after the local forwprop optimizations
instead of before.

There was already code to add to to_purge after forward_propagate_into_comparison and removes
that as it is now redundant.

gcc/ChangeLog:

	* tree-ssa-forwprop.cc (pass_forwprop::execute): Move marking of to_purge bb
	and marking of fixup statements to after the local optimizations.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>