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/RallocUtil.c b/vm/compiler/codegen/RallocUtil.c
index 5116243..27d1f05 100644
--- a/vm/compiler/codegen/RallocUtil.c
+++ b/vm/compiler/codegen/RallocUtil.c
@@ -448,7 +448,7 @@
         LIR *p;
         assert(sReg1 == sReg2);
         for (p = start; ;p = p->next) {
-            ((ArmLIR *)p)->isNop = true;
+            ((ArmLIR *)p)->flags.isNop = true;
             if (p == finish)
                 break;
         }