[llvm] [Support] Include Support/thread.h before api implementations (PR #111175)

[Saleem Abdulrasool via llvm-commits]

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@@ -33,6 +33,13 @@
 #include <pthread_np.h> // For pthread_getthreadid_np() / pthread_set_name_np()
 #endif
 
+// Must be included after Threading.inc to provide definition for llvm::thread
+// because FreeBSD's condvar.h (included by user.h) misuses the "thread"
+// keyword.
+#ifndef __FreeBSD__
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compnerd wrote:

I wonder if we should just undef thread instead on FreeBSD. I think that we can just do this for now, it is more conservative.

https://github.com/llvm/llvm-project/pull/111175