Support: add support to identify WinCOFF/ARM objects

Add the Windows COFF ARM object file magic.  This enables the LLVM tools to
interact with COFF object files for Windows on ARM.

llvm-svn: 203761
diff --git a/llvm/lib/Object/COFFObjectFile.cpp b/llvm/lib/Object/COFFObjectFile.cpp
index 6ef2fbf..461dbac 100644
--- a/llvm/lib/Object/COFFObjectFile.cpp
+++ b/llvm/lib/Object/COFFObjectFile.cpp
@@ -663,6 +663,8 @@
     return "COFF-i386";
   case COFF::IMAGE_FILE_MACHINE_AMD64:
     return "COFF-x86-64";
+  case COFF::IMAGE_FILE_MACHINE_ARMNT:
+    return "COFF-ARM";
   default:
     return "COFF-<unknown arch>";
   }
@@ -674,6 +676,8 @@
     return Triple::x86;
   case COFF::IMAGE_FILE_MACHINE_AMD64:
     return Triple::x86_64;
+  case COFF::IMAGE_FILE_MACHINE_ARMNT:
+    return Triple::thumb;
   default:
     return Triple::UnknownArch;
   }