Add ARM Archv6M and let it implies FeatureDB (having dmb, etc.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110795 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMSubtarget.h b/lib/Target/ARM/ARMSubtarget.h
index 4e08e57..c5b3402 100644
--- a/lib/Target/ARM/ARMSubtarget.h
+++ b/lib/Target/ARM/ARMSubtarget.h
@@ -26,7 +26,7 @@
 class ARMSubtarget : public TargetSubtarget {
 protected:
   enum ARMArchEnum {
-    V4, V4T, V5T, V5TE, V6, V6T2, V7A, V7M
+    V4, V4T, V5T, V5TE, V6, V6M, V6T2, V7A, V7M
   };
 
   enum ARMFPEnum {