Give helper classes/functions local linkage. NFC.

llvm-svn: 351016
diff --git a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
index 8291239..9af64ed 100644
--- a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -185,7 +185,7 @@
 /// Prefer relative paths in the coverage notes. Clang also may split
 /// up absolute paths into a directory and filename component. When
 /// the relative path doesn't exist, reconstruct the absolute path.
-SmallString<128> getFilename(const DISubprogram *SP) {
+static SmallString<128> getFilename(const DISubprogram *SP) {
   SmallString<128> Path;
   StringRef RelPath = SP->getFilename();
   if (sys::fs::exists(RelPath))