Apply most suggestions of clang-tidy's performance-unnecessary-value-param

Avoids unnecessary copies. All changes audited & pass tests with asan.
No functional change intended.

llvm-svn: 272190
diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index b0facfb..7079ed2 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -114,7 +114,7 @@
 /// If the input path is a .dSYM bundle (as created by the dsymutil tool),
 /// replace it with individual entries for each of the object files inside the
 /// bundle otherwise return the input path.
-static std::vector<std::string> expandBundle(std::string InputPath) {
+static std::vector<std::string> expandBundle(const std::string &InputPath) {
   std::vector<std::string> BundlePaths;
   SmallString<256> BundlePath(InputPath);
   // Manually open up the bundle to avoid introducing additional dependencies.