Make helper functions static.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175265 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 433e767..66d698a 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -196,8 +196,7 @@
     FD->hasBody(Def) && Def->isInlined() && !Def->hasAttr<GNUInlineAttr>();
 }
 
-template<typename T>
-bool isInExternCContext(T *D) {
+template <typename T> static bool isInExternCContext(T *D) {
   const T *First = D->getFirstDeclaration();
   return First->getDeclContext()->isExternCContext();
 }