Quick compiler - fix run-test 019

Two problems:
  1.  Was treating an array object store as a regular array store
  2.  Codegen bug that (somewhat disturbingly) existed in the
      non-quick code.  I'm a little surprised that it hadn't
      shown up before now, but it would tend to be masked if
      the array base register in question was promoted.

Change-Id: I62bcb866174538ceedcc1309edcf22261237840a
diff --git a/src/compiler/codegen/arm/ArchUtility.cc b/src/compiler/codegen/arm/ArchUtility.cc
index 725200a..cdb8486 100644
--- a/src/compiler/codegen/arm/ArchUtility.cc
+++ b/src/compiler/codegen/arm/ArchUtility.cc
@@ -218,6 +218,8 @@
              sprintf(tbuf,"%d", operand);
              break;
            case 'C':
+             DCHECK_LT(operand, static_cast<int>(
+                 sizeof(coreRegNames)/sizeof(coreRegNames[0])));
              sprintf(tbuf,"%s",coreRegNames[operand]);
              break;
            case 'E':