Quick compiler: debugging assists

A few minor assists to ease A/B debugging in the Quick
compiler:
   1.  To save time, the assemblers for some targets only
update the object code offsets on instructions involved with
pc-relative fixups.  We add code to fix up all offsets when
doing a verbose codegen listing.
   2.  Temp registers are normally allocated in a round-robin
fashion.  When disabling liveness tracking, we now reset the
round-robin pool to 0 on each instruction boundary.  This makes
it easier to spot real codegen differences.
   3.  Self-register copies were previously emitted, but
marked as nops.  Minor change to avoid generating them in the
first place and reduce clutter.

Change-Id: I7954bba3b9f16ee690d663be510eac7034c93723
diff --git a/compiler/dex/quick/mir_to_lir.cc b/compiler/dex/quick/mir_to_lir.cc
index 6d38488..b8ab609 100644
--- a/compiler/dex/quick/mir_to_lir.cc
+++ b/compiler/dex/quick/mir_to_lir.cc
@@ -990,6 +990,9 @@
     ResetRegPool();
     if (cu_->disable_opt & (1 << kTrackLiveTemps)) {
       ClobberAllRegs();
+      // Reset temp allocation to minimize differences when A/B testing.
+      reg_pool_->next_core_reg = 0;
+      reg_pool_->next_fp_reg = 0;
     }
 
     if (cu_->disable_opt & (1 << kSuppressLoads)) {