libclang: introduce cxstring::{createRef,createDup} for StringRefs

Also migrate all clients from the old API.

llvm-svn: 174263
diff --git a/clang/tools/libclang/CXStoredDiagnostic.cpp b/clang/tools/libclang/CXStoredDiagnostic.cpp
index a8d2aa0..f2d102a 100644
--- a/clang/tools/libclang/CXStoredDiagnostic.cpp
+++ b/clang/tools/libclang/CXStoredDiagnostic.cpp
@@ -49,7 +49,7 @@
 }
 
 CXString CXStoredDiagnostic::getSpelling() const {
-  return createCXString(Diag.getMessage(), false);
+  return cxstring::createRef(Diag.getMessage());
 }
 
 CXString CXStoredDiagnostic::getDiagnosticOption(CXString *Disable) const {
@@ -57,8 +57,8 @@
   StringRef Option = DiagnosticIDs::getWarningOptionForDiag(ID);
   if (!Option.empty()) {
     if (Disable)
-      *Disable = createCXString((Twine("-Wno-") + Option).str());
-    return createCXString((Twine("-W") + Option).str());
+      *Disable = cxstring::createDup((Twine("-Wno-") + Option).str());
+    return cxstring::createDup((Twine("-W") + Option).str());
   }
   
   if (ID == diag::fatal_too_many_errors) {
@@ -76,7 +76,7 @@
 
 CXString CXStoredDiagnostic::getCategoryText() const {
   unsigned catID = DiagnosticIDs::getCategoryNumberForDiag(Diag.getID());
-  return createCXString(DiagnosticIDs::getCategoryNameFromID(catID));
+  return cxstring::createRef(DiagnosticIDs::getCategoryNameFromID(catID));
 }
 
 unsigned CXStoredDiagnostic::getNumRanges() const {
@@ -109,6 +109,6 @@
     *ReplacementRange = translateSourceRange(Diag.getLocation().getManager(),
                                              LangOpts, Hint.RemoveRange);
   }
-  return createCXString(Hint.CodeToInsert);
+  return cxstring::createDup(Hint.CodeToInsert);
 }