Register promotion support for 64-bit targets

Not sufficiently tested for 64-bit targets, but should be
fairly close.

A significant amount of refactoring could stil be done, (in
later CLs).

With this change we are not making any changes to the vmap
scheme.  As a result, it is a requirement that if a vreg
is promoted to both a 32-bit view and the low half of a
64-bit view it must share the same physical register.  We
may change this restriction later on to allow for more flexibility
for 32-bit Arm.

For example, if v4, v5, v4/v5 and v5/v6 are all hot enough to
promote, we'd end up with something like:

v4 (as an int)    -> r10
v4/v5 (as a long) -> r10
v5 (as an int)    -> r11
v5/v6 (as a long) -> r11

Fix a couple of ARM64 bugs on the way...

Change-Id: I6a152b9c164d9f1a053622266e165428045362f3
diff --git a/compiler/dex/quick/mir_to_lir-inl.h b/compiler/dex/quick/mir_to_lir-inl.h
index 9a62255..9ce5bb7 100644
--- a/compiler/dex/quick/mir_to_lir-inl.h
+++ b/compiler/dex/quick/mir_to_lir-inl.h
@@ -31,7 +31,7 @@
     p->MarkDead();
     if (p->IsWide()) {
       p->SetIsWide(false);
-      if (p->GetReg() != p->Partner()) {
+      if (p->GetReg().NotExactlyEquals(p->Partner())) {
         // Register pair - deal with the other half.
         p = GetRegInfo(p->Partner());
         p->SetIsWide(false);