ARM: allow cortex-m0 to use hint instructions

The hint instructions ("nop", "yield", etc) are mostly Thumb2-only, but have
been ported across to the v6M architecture. Fortunately, v6M seems to sit
nicely between v6 (thumb-1 only) and v6T2, so we can add a feature for it
fairly easily.

rdar://problem/15144406

llvm-svn: 192097
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index 11d8e8e..7c7e402 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -44,12 +44,13 @@
   ARMProcClassEnum ARMProcClass;
 
   /// HasV4TOps, HasV5TOps, HasV5TEOps,
-  /// HasV6Ops, HasV6T2Ops, HasV7Ops, HasV8Ops -
+  /// HasV6Ops, HasV6MOps, HasV6T2Ops, HasV7Ops, HasV8Ops -
   /// Specify whether target support specific ARM ISA variants.
   bool HasV4TOps;
   bool HasV5TOps;
   bool HasV5TEOps;
   bool HasV6Ops;
+  bool HasV6MOps;
   bool HasV6T2Ops;
   bool HasV7Ops;
   bool HasV8Ops;