* Add local_function field to context
* Add local call indirection to llvm
* local call indirection
* Fix vm test
* Fix cranelift local call indirection
* Fix unwinding on nightly
Implementation Notes:
- To avoid setjmp, longjmp, and the mess that those create, we instead set the interrupting
context of the signal handler to return into the `throw_trap` routine. To my surprise,
this actually works. The stack ends up getting unwound normally and the memory-oob error
is caught by the trampoline.