Swap loop splitting and final value replacement

Swap loop splitting and final value replacement

The following swaps the loop splitting pass and the final value
replacement pass to avoid keeping the IV of the earlier loop
live when not necessary.  The existing gcc.target/i386/pr87007-5.c
testcase shows that we otherwise fail to elide an empty loop
later.  I don't see any good reason why loop splitting would need
final value replacement, all exit values honor the constraints
we place on loop header PHIs automatically.

	* passes.def: Exchange loop splitting and final value
	replacement passes.

	* gcc.target/i386/pr87007-5.c: Make sure we split the loop
	and eliminate both in the end.