Use a more direct check for finding out the file type.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196811 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCObjectFileInfo.h

@@ -353,8 +353,12 @@ public:
     return EHFrameSection;
   }
 
-private:
   enum Environment { IsMachO, IsELF, IsCOFF };
+  Environment getObjectFileType() const {
+    return Env;
+  }
+
+private:
   Environment Env;
   Reloc::Model RelocM;
   CodeModel::Model CMModel;