MSVC is stuck in the 80s.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140597 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/libclang.exports b/tools/libclang/libclang.exports
index 71cd261..019110a 100644
--- a/tools/libclang/libclang.exports
+++ b/tools/libclang/libclang.exports
@@ -21,6 +21,7 @@
 clang_createTranslationUnit
 clang_createTranslationUnitFromSourceFile
 clang_Cursor_getTranslationUnit
+clang_Cursor_isNull
 clang_defaultCodeCompleteOptions
 clang_defaultDiagnosticDisplayOptions
 clang_defaultEditingTranslationUnitOptions