Change the order of waiting for term and checking

Change the order of waiting for term and checking

This is done so that a philosopher truly cannot write to terminal after
it dies. Before this commit, a philosopher that is alive would wait for
term semaphore. Meanwhile something could change his state to not alive
but he could then get the semaphore and print anyway.

I thought about having the condition inside as well as on the outside
of the sem_wait. But having it just after the sem_wait should be
alright.