[PATCH, testsuite]: Do not run simulate-thread on alpha*-*-linux*

[Dominique Dhumieres]

Hi Uros,

Is your patch dealing with gcc.dg/simulate-thread/atomic-other-* running
for ever without timeout? If yes, I have seen the same problem on 
powerpc-apple-darwin9. Could you add powerpc*-apple-darwin* to your
patch?

TIA

Dominique