Use private linkage to avoid symbol conflicts in corner cases like the one
in PR9301.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126422 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 844b1e3..f4db01d 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -642,7 +642,7 @@
         // candidate nor a __block variable, emit it as a global instead.
         if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
             !NRVO && !isByRef) {
-          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
+          EmitStaticVarDecl(D, llvm::GlobalValue::PrivateLinkage);
 
           emission.Address = 0; // signal this condition to later callbacks
           assert(emission.wasEmittedAsGlobal());