ModuleLinker: Do not import linkonce/weak as "external_weak"

Summary:
There is no reason to have a weak reference because the external
definition will be weak.

Reviewers: rafael

Subscribers: llvm-commits, tejohnson

Differential Revision: http://reviews.llvm.org/D19267

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266750
diff --git a/llvm/test/Linker/comdat14.ll b/llvm/test/Linker/comdat14.ll
index 793f857..9c6eb7c 100644
--- a/llvm/test/Linker/comdat14.ll
+++ b/llvm/test/Linker/comdat14.ll
@@ -5,5 +5,5 @@
 @v = global i32 0, comdat ($c)
 
 ; CHECK: @v = global i32 0, comdat($c)
-; CHECK: @v2 = extern_weak dllexport global i32
-; CHECK: @v3 = extern_weak global i32
+; CHECK: @v2 = external dllexport global i32
+; CHECK: @v3 = external global i32