Correct setting of UserLabelPrefix for MCU target.

Differential Revision: http://reviews.llvm.org/D16138

llvm-svn: 257756

clang/lib/Basic/Targets.cpp

@@ -3899,6 +3899,7 @@ public:
   MCUX86_32TargetInfo(const llvm::Triple &Triple) : X86_32TargetInfo(Triple) {
     LongDoubleWidth = 64;
     LongDoubleFormat = &llvm::APFloat::IEEEdouble;
+    UserLabelPrefix = "";
   }
 
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {

clang/test/Preprocessor/elfiamcu-predefines.c

@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -E -dM -triple i586-intel-elfiamcu | FileCheck %s
 
+// CHECK: #define __USER_LABEL_PREFIX__ {{$}}
 // CHECK: #define __iamcu
 // CHECK: #define __iamcu__