Decrease the visibility of the ENABLE_THREADING_XX guards.

Source/wtf/ParallelJobs.h

 /*
  * Copyright (C) 2011 University of Szeged
  * Copyright (C) 2011 Gabor Loki <loki@webkit.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 31 matching lines @@
 //     for(i = 0; i < parallelJobs.numberOfJobs(); ++i) {
 //       TypeOfParameter& params = parallelJobs.parameter(i);
 //       params.attr1 = localVars ...
 //       ...
 //     }
 //
 //     // Execute parallel jobs
 //     parallelJobs.execute();
 //
 
+#if !defined(ENABLE_THREADING_LIBDISPATCH) && HAVE(DISPATCH_H)
+#define ENABLE_THREADING_LIBDISPATCH 1
+#elif !defined(THREADING_GENERIC)
+#define ENABLE_THREADING_GENERIC 1
+#endif
+
 #if ENABLE(THREADING_GENERIC)
 #include <wtf/ParallelJobsGeneric.h>
 
-#elif ENABLE(THREADING_OPENMP)
-#include <wtf/ParallelJobsOpenMP.h>
-
 #elif ENABLE(THREADING_LIBDISPATCH)
 #include <wtf/ParallelJobsLibdispatch.h>
 
 #else
 #error "No parallel processing API for ParallelJobs"
 
 #endif
 
 namespace WTF {
 
@@ skipping 28 matching lines @@
 private:
     ParallelEnvironment m_parallelEnvironment;
     Vector<Type> m_parameters;
 };
 
 } // namespace WTF
 
 using WTF::ParallelJobs;
 
 #endif // ParallelJobs_h