Patches for PR34421, 34514, 34533, and 34536

[Dominique Dhumieres]

I have applied the patches for PR34421, 34514, 34533, and 34536 on top
of at least revision 131139. As far as I can tell, they work as expected
without regression on ppc and intel Darwin9.

As discussed with Daniel on IRC, it would probably nice to test that
dtime does cause deadlock with omp codes, but I don't know what to do
for that.

Thanks for the patches and happy holidays to everybody.

Dominique