Always (re)initialize thread frame pointers.
Always (re)initialize thread frame pointers.

This isn't strictly needed for regular threads, but without it ephemeral
threads can end up with loops in their stack frames.

varjagg/Mezzano,rvedam/Mezzano,AugustusHuang/Mezzano,AugustusHuang/Mezzano,rvedam/Mezzano,froggey/Mezzano,varjagg/Mezzano,froggey/Mezzano