Move CXString creation/management routines into
their own .cpp file and make the interpretation
of its flags private.

llvm-svn: 119319
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index f3ba997..c8af349 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -134,9 +134,7 @@
  */
 typedef struct {
   const char *Spelling;
-  /* A 1 value indicates the clang_ indexing API needed to allocate the string
-     (and it must be freed by clang_disposeString()). */
-  int MustFreeString;
+  unsigned private_flags;
 } CXString;
 
 /**