exa2pro/starpu-max: porting work to Maxeler DFE @ 59a34928f906c395e9033546e48f45fc352d9c6d

Samuel Thibault 64ca2ebf8a Fix cast order		12 lat temu
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pthread.h	64ca2ebf8a Fix cast order	12 lat temu
semaphore.h	c6b65fe5f8 re-introduce the thin pthread-to-win32 layer, as an option, as it seems recent versions of mingw and cygwin use a new pthread library which does not play well with starpu.	13 lat temu