Merge branch 'jetjaw-crash-fix' into 'next'

Jet Jaw crash fix

Turns out not having MF_SHOOTABLE can cause the Jet Jaw to endlessly loop between the two states, until somehow LUA_CallAction inexplicably causes Z_StrDup to crash anyway (that one's a mystery to me, I'm not going to look into it right now). I tweaked A_JetJawChomp so this endless loop can't happen anymore.

See merge request !176