[llvm-cgdata] Fix Dangling StringRefs (#143210)

Author: NuriAmari

llvm/tools/llvm-cgdata/llvm-cgdata.cpp

@@ -75,8 +75,8 @@ class CGDataOptTable : public opt::GenericOptTable {
 
 // Options
 static StringRef ToolName;
-static StringRef OutputFilename = "-";
-static StringRef Filename;
+static std::string OutputFilename = "-";
+static std::string Filename;
 static bool ShowCGDataVersion;
 static bool SkipTrim;
 static CGDataAction Action;