[ARM] Improve build attributes emission.

llvm-svn: 192111
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
index 2beb500..de8e3f8 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
@@ -149,7 +149,7 @@
         isThumb = true;
         if (NoCPU)
           // v6m: FeatureNoARM, FeatureMClass
-          ARMArchFeature = "+v6,+noarm,+mclass";
+          ARMArchFeature = "+v6m,+noarm,+mclass";
         else
           ARMArchFeature = "+v6";
       } else