Cleanup handling of UniqueExternalLinkage.

This patch renames getLinkage to getLinkageInternal. Only code that
needs to handle UniqueExternalLinkage specially should call this.

Linkage, as defined in the c++ standard, is provided by
getFormalLinkage. It maps UniqueExternalLinkage to ExternalLinkage.

Most places in the compiler actually want isExternallyVisible, which
handles UniqueExternalLinkage as internal.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181677 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index d28aced..3137f3c 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -405,7 +405,7 @@
     if (DC->isFunctionOrMethod() && D->hasLinkage())
       while (!DC->isNamespace() && !DC->isTranslationUnit())
         DC = getEffectiveParentContext(DC);
-    if (DC->isTranslationUnit() && D->getLinkage() != InternalLinkage)
+    if (DC->isTranslationUnit() && D->getFormalLinkage() != InternalLinkage)
       return false;
   }
 
@@ -1053,7 +1053,7 @@
       //   static void foo();
       // This naming convention is the same as that followed by GCC,
       // though it shouldn't actually matter.
-      if (ND && ND->getLinkage() == InternalLinkage &&
+      if (ND && ND->getFormalLinkage() == InternalLinkage &&
           getEffectiveDeclContext(ND)->isFileContext())
         Out << 'L';