Make last DCE remove empty loops

Make last DCE remove empty loops

The following makes the last DCE pass CD-DCE and in turn the
last CD-DCE pass a DCE one.  That ensues we remove empty loops
that become empty between the two.  I've also moved the tail-call
pass after DCE since DCE can only improve things here.

The two testcases were the only ones scanning cddce3 so I've
changed them to scan the dce7 pass that's now in this place.
The testcases scanning dce7 also work when that's in the earlier
position.

	PR tree-optimization/84646
	* tree-ssa-dce.cc (pass_dce::set_pass_param): Add param
	wheter to run update-address-taken.
	(pass_dce::execute): Honor it.
	* passes.def: Exchange last DCE and CD-DCE invocations.
	Swap pass_tail_calls and the last DCE.

	* g++.dg/tree-ssa/pr106922.C: Continue to scan earlier DCE dump.
	* gcc.dg/tree-ssa/20030808-1.c: Likewise.