Add a file magic for CL.exe's object file created with /GL.

This patch makes it possible to identify object files created by CL.exe
with /GL option. Such file contains Microsoft proprietary intermediate
code instead of target machine code to do LTO.

I need this to print out user-friendly error message from LLD.

Differential Revision: https://reviews.llvm.org/D26645

llvm-svn: 286919

llvm/lib/Object/ObjectFile.cpp

@@ -78,6 +78,7 @@ ObjectFile::createObjectFile(MemoryBufferRef Object, sys::fs::file_magic Type) {
   switch (Type) {
   case sys::fs::file_magic::unknown:
   case sys::fs::file_magic::bitcode:
+  case sys::fs::file_magic::coff_cl_gl_object:
   case sys::fs::file_magic::archive:
   case sys::fs::file_magic::macho_universal_binary:
   case sys::fs::file_magic::windows_resource: