libclang: cleanup unused includes in public header


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188625 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/Indexing.cpp b/tools/libclang/Indexing.cpp
index 48fd43b..98395e6 100644
--- a/tools/libclang/Indexing.cpp
+++ b/tools/libclang/Indexing.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/MutexGuard.h"
+#include <stdio.h>
 
 using namespace clang;
 using namespace cxtu;