Misc goodies in the JIT in preparation for more aggressive code motion.

- Set up resource masks correctly for Thumb push/pop when LR/PC are involved.
- Preserve LR around simulated heap references under self-verification mode.
- Compact a few simple flags in ArmLIR into bit fields.
- Minor performance tuning in TEMPLATE_MEM_OP_DECODE

Change-Id: Id73edac837c5bb37dfd21f372d6fa21c238cf42a
diff --git a/vm/compiler/codegen/arm/GlobalOptimizations.c b/vm/compiler/codegen/arm/GlobalOptimizations.c
index c1e69c3..872bddf 100644
--- a/vm/compiler/codegen/arm/GlobalOptimizations.c
+++ b/vm/compiler/codegen/arm/GlobalOptimizations.c
@@ -41,7 +41,7 @@
                  * Is the branch target the next instruction?
                  */
                 if (nextLIR == (ArmLIR *) thisLIR->generic.target) {
-                    thisLIR->isNop = true;
+                    thisLIR->flags.isNop = true;
                     break;
                 }