Have LowerOperandForConstraint handle multiple character constraints.

Part of rdar://9119939


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132510 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 8ef0601..21a9a3a 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -315,7 +315,7 @@
     /// true it means one of the asm constraint of the inline asm instruction
     /// being processed is 'm'.
     virtual void LowerAsmOperandForConstraint(SDValue Op,
-                                              char ConstraintLetter,
+                                              std::string &Constraint,
                                               std::vector<SDValue> &Ops,
                                               SelectionDAG &DAG) const;