SourceKit: correct header include order

Internal.h must be included before sourcekitd.h to ensure that we get the
correct definition for Windows targets.  The inclusion of `sourcekitd.h` is not
needed after the inclusion of `Internal.h` so simply remove the inclusion.

Author: compnerd

tools/SourceKit/tools/sourcekitd/lib/API/sourcekitdAPI-InProc.cpp

@@ -11,7 +11,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "DictionaryKeys.h"
-#include "sourcekitd/sourcekitd.h"
 #include "sourcekitd/Internal.h"
 #include "sourcekitd/CodeCompletionResultsArray.h"
 #include "sourcekitd/DocStructureArray.h"