[MinGW] Define __ARM_DWARF_EH__ on MinGW/ARM

[mstorsjo]

Summary

This should go together with D39532 in LLVM.

cfe/trunk/lib/Basic/Targets/ARM.cpp

 }
 
 void MinGWARMTargetInfo::getTargetDefines(const LangOptions &Opts,
                                           MacroBuilder &Builder) const {
   WindowsARMTargetInfo::getTargetDefines(Opts, Builder);
   DefineStd(Builder, "WIN32", Opts);
   DefineStd(Builder, "WINNT", Opts);
   Builder.defineMacro("_ARM_");
+  Builder.defineMacro("__ARM_DWARF_EH__");
   addMinGWDefines(Opts, Builder);
 }
 
 CygwinARMTargetInfo::CygwinARMTargetInfo(const llvm::Triple &Triple,
                                          const TargetOptions &Opts)
     : ARMleTargetInfo(Triple, Opts) {
   this->WCharType = TargetInfo::UnsignedShort;
   TLSSupported = false;

cfe/trunk/test/Preprocessor/init.c

 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=thumbv7 < /dev/null | FileCheck -match-full-lines -check-prefix Thumbv7 %s
 // Thumbv7: #define __THUMB_INTERWORK__ 1
 // Thumbv7: #define __thumb2__ 1
 
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=thumbebv7 < /dev/null | FileCheck -match-full-lines -check-prefix Thumbebv7 %s
 // Thumbebv7: #define __THUMB_INTERWORK__ 1
 // Thumbebv7: #define __thumb2__ 1
 
+// RUN: %clang -E -dM -ffreestanding -target thumbv7-pc-mingw32 %s -o - | FileCheck -match-full-lines -check-prefix THUMB-MINGW %s
+
+// THUMB-MINGW:#define __ARM_DWARF_EH__ 1
+
 //
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-none-none < /dev/null | FileCheck -match-full-lines -check-prefix I386 %s
 //
 // I386-NOT:#define _LP64
 // I386:#define __BIGGEST_ALIGNMENT__ 16
 // I386:#define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__
 // I386:#define __CHAR16_TYPE__ unsigned short
 // I386:#define __CHAR32_TYPE__ unsigned int