libclang: Add clang_executeOnThread, for use in c-index-test (and only there,
preferably). Good thing c-index-test is written in C!!!!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@118223 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 3afe300..0d660da 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -3562,6 +3562,11 @@
   llvm::sys::PrintStackTraceOnErrorSignal();
 }
 
+void clang_executeOnThread(void (*fn)(void*), void *user_data,
+                           unsigned stack_size) {
+  llvm::llvm_execute_on_thread(fn, user_data, stack_size);
+}
+
 } // end: extern "C"
 
 //===----------------------------------------------------------------------===//