Fix libgomp semaphores

[Alan Modra]

On Fri, Nov 25, 2011 at 08:38:39AM +0100, Jakub Jelinek wrote:
> My preference would be to avoid the abstraction changes though, both
> because it is additional clutter in the changeset and because omp_lock
> and nested lock are part of public ABIs, so if struct is layed out
> differently on some weird architecture, it would be an ABI change.

OK, fair enough.  I didn't consider that structs may be laid out
differently.

> So, if you could keep gomp_mutex_t, omp_lock_t and gomp_sem_t as integers,
> it would be appreciated.
> 
> Furthermore, I'd prefer if the patch could be split into smaller parts,
> e.g. for bisecting purposes.  One patch would do the mutex changes
> to use new atomics, remove extra mutex.h headers and start using 0/1/-1
> instead of 0/1/2.  And another patch would rewrite the semaphores.

OK.  I need to do this anyway as I just discovered a regression when
looping on one of the tests.  I suspect the acquire/release mutex
locking may have exposed bugs elsewhere in libgomp that were covered
by the heavyweight locking used by the __sync builtins.

-- 
Alan Modra
Australia Development Lab, IBM