Previously wasmtime would handle any signal originating from wasm JIT code. This would, however, handle bugs in JIT code as-if they were wasm traps. Instead this commit switches signal handling to specifically check for whether the precise program counter is expected to be a trap. This way if a program counter traps and it's not expected to trap the signal isn't handled and the process is aborted (presumably leading to further debugging of whomever happens to work on the JIT at that time).
This is the wasmtime-runtime crate, which contains wasm runtime library
support, supporting the wasm ABI used by wasmtime-environ,
wasmtime-jit, and wasmtime-obj.
This crate does not make a host vs. target distinction; it is meant to be compiled for the target.
Most users will want to use the main wasmtime crate instead of using this
crate directly.