Remove several .c_str() to be forward-compatible with StringRef.

llvm-svn: 90822
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 2b823e0..56ee63f 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -137,8 +137,8 @@
 
   // Create new compile unit.
   return Unit = DebugFactory.CreateCompileUnit(LangTag, 
-                                               AbsFileName.getLast().c_str(),
-                                               AbsFileName.getDirname().c_str(),
+                                               AbsFileName.getLast(),
+                                               AbsFileName.getDirname(),
                                                Producer.c_str(), isMain, 
                                                isOptimized, Flags, RuntimeVers);
 }