Object/COFF: Support common symbols.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144861 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Object/COFFObjectFile.cpp b/lib/Object/COFFObjectFile.cpp
index 2abfb44..c6ce562 100644
--- a/lib/Object/COFFObjectFile.cpp
+++ b/lib/Object/COFFObjectFile.cpp
@@ -226,7 +226,9 @@
     if (symb->StorageClass == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL) {
       Result = 'w';
       return object_error::success; // Don't do ::toupper.
-    } else
+    } else if (symb->Value != 0) // Check for common symbols.
+      ret = 'c';
+    else
       ret = 'u';
     break;
   case COFF::IMAGE_SYM_ABSOLUTE: