Add ASTUnit::getOriginalSourceFileName() and use in clang_getTranslationUnitSpelling().

llvm-svn: 80932
diff --git a/clang/tools/CIndex/CIndex.cpp b/clang/tools/CIndex/CIndex.cpp
index 5d1ee96..ef285e0 100644
--- a/clang/tools/CIndex/CIndex.cpp
+++ b/clang/tools/CIndex/CIndex.cpp
@@ -194,9 +194,8 @@
 const char *clang_getTranslationUnitSpelling(CXTranslationUnit CTUnit)
 {
   assert(CTUnit && "Passed null CXTranslationUnit");
-  //ASTUnit *CXXUnit = static_cast<ASTUnit *>(CTUnit);
-  //return CXXUnit->getOriginalSourceFileName().c_str();
-  return "<unimplemented>";
+  ASTUnit *CXXUnit = static_cast<ASTUnit *>(CTUnit);
+  return CXXUnit->getOriginalSourceFileName().c_str();
 }
 
 void clang_loadTranslationUnit(CXTranslationUnit CTUnit,