gimple: sccopy: Don't increment i after vec::unordered_remove()

gimple: sccopy: Don't increment i after vec::unordered_remove()

I increment the index variable in a loop even when I do
vec::unordered_remove() which causes the vector traversal to miss some
elements.  Mikael notified me of this mistake I made in my last patch.

gcc/ChangeLog:

	* gimple-ssa-sccopy.cc (scc_copy_prop::propagate): Don't
	increment after vec::unordered_remove().

Reported-by: Mikael Morin <mikael@gcc.gnu.org>
Signed-off-by: Filip Kastl <fkastl@suse.cz>