moribund threads initiating GC

[Nikodemus Siivola]

Moribund threads have been reported initiating GC.

Part of the problem is easy to fix: bind *current-thread* in the C-side
trampoline so that it remains valid after the lisp code for the thread
has finished (and check it in sub-gc.)

Understanding why and how a moribund thread can enter SUB-GC
would be crucial, however.

Sadly, I have not been able to replicate this for a while. This is
sufficiently bogus, however, that diagnosing the problem in depth
on a legacy SBCL is probably worthwhile.

[Douglas Katzman (dougk)]

i doubt this is true any more. resolving as invalid