Quick: Fix and enable DCE and improve GVN/DCE cleanup.

When eliminating a move by renaming its source register,
check that it doesn't conflict with vreg usage by insns
between the defining insn and the move.

Improve the GVN/DCE cleanup so that it can handle cases
where GVN or DCE is individually disabled in the pass driver
but not in the disable_opt flags.

Bug: 19419671
Change-Id: I49bb67b81509f51fbaf90c6016c509962be43736
diff --git a/compiler/dex/pass_driver_me_opts.cc b/compiler/dex/pass_driver_me_opts.cc
index 2e871da..3e193b4 100644
--- a/compiler/dex/pass_driver_me_opts.cc
+++ b/compiler/dex/pass_driver_me_opts.cc
@@ -46,6 +46,7 @@
   pass_manager->AddPass(new CodeLayout);
   pass_manager->AddPass(new GlobalValueNumberingPass);
   pass_manager->AddPass(new DeadCodeEliminationPass);
+  pass_manager->AddPass(new GlobalValueNumberingCleanupPass);
   pass_manager->AddPass(new ConstantPropagation);
   pass_manager->AddPass(new MethodUseCount);
   pass_manager->AddPass(new BBOptimizations);