remove __wasi_proc_raise() #7
Description
From bytecodealliance/wasmtime#68:
__wasi_proc_raise in its current form is effectively just a variant of __wasi_proc_exit which produces an exit status indicating that the process was killed with a signal rather than exiting normally.
I agree that this is obscure, and it could create complications if real signal handling is added later, so we should consider removing it.