[libclang] Introduce clang_Range_isNull.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140706 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/libclang.exports b/tools/libclang/libclang.exports
index 4ebbf9e..89d4131 100644
--- a/tools/libclang/libclang.exports
+++ b/tools/libclang/libclang.exports
@@ -142,6 +142,7 @@
 clang_isVirtualBase
 clang_isVolatileQualifiedType
 clang_parseTranslationUnit
+clang_Range_isNull
 clang_remap_dispose
 clang_remap_getFilenames
 clang_remap_getNumFiles