[project @ 2000-01-22 18:00:03 by simonmar]
Fix bug in async exception handling: the target TSO may have been relocated as a result of a stack overflow. Introduce a new StgTSOWhatNext value "ThreadRelocated", which indicates that this TSO has moved, and the new location is in the link field. The garbage collector shorts these out just like indirections. We have to check for relocated TSOs in killThread# (and any other primops which take a ThreadId# as an argument - there aren't any at present).