libclang: add new StringSet type

This allows the return of a set of CXStrings from libclang.  This is setup work
for an upcoming change to permit returning multiple mangled symbols.

llvm-svn: 252852
diff --git a/clang/include/clang-c/CXString.h b/clang/include/clang-c/CXString.h
index a649cdf..68ab7bc 100644
--- a/clang/include/clang-c/CXString.h
+++ b/clang/include/clang-c/CXString.h
@@ -40,6 +40,11 @@
   unsigned private_flags;
 } CXString;
 
+typedef struct {
+  CXString *Strings;
+  unsigned Count;
+} CXStringSet;
+
 /**
  * \brief Retrieve the character data associated with the given string.
  */
@@ -51,6 +56,11 @@
 CINDEX_LINKAGE void clang_disposeString(CXString string);
 
 /**
+ * \brief Free the given string set.
+ */
+CINDEX_LINKAGE void clang_disposeStringSet(CXStringSet *set);
+
+/**
  * @}
  */