[libclang] Expose warn_unused and warn_unused_result attributes.

This is helpful to properly detect them, and fixing issues like
https://github.com/rust-lang/rust-bindgen/issues/1518.

Differential Revision: https://reviews.llvm.org/D58570

llvm-svn: 354824
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 38af8aa..e6555fa 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -32,7 +32,7 @@
  * compatible, thus CINDEX_VERSION_MAJOR is expected to remain stable.
  */
 #define CINDEX_VERSION_MAJOR 0
-#define CINDEX_VERSION_MINOR 51
+#define CINDEX_VERSION_MINOR 52
 
 #define CINDEX_VERSION_ENCODE(major, minor) ( \
       ((major) * 10000)                       \
@@ -2587,7 +2587,9 @@
   CXCursor_ObjCBoxable                   = 436,
   CXCursor_FlagEnum                      = 437,
   CXCursor_ConvergentAttr                = 438,
-  CXCursor_LastAttr                      = CXCursor_ConvergentAttr,
+  CXCursor_WarnUnusedAttr                = 439,
+  CXCursor_WarnUnusedResultAttr          = 440,
+  CXCursor_LastAttr                      = CXCursor_WarnUnusedResultAttr,
 
   /* Preprocessing */
   CXCursor_PreprocessingDirective        = 500,