This changes the AssemblyScript abort handler and WASI proc_exit
implementation to panic the caller which eventually invoked close.
This ensures no code executes afterwards, For example, LLVM inserts
unreachable instructions after calls to exit.
See https://github.com/emscripten-core/emscripten/issues/12322
See #601
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This adds two clock interfaces: sys.Walltime and sys.Nanotime to
allow implementations to override readings for purposes of security or
determinism.
The default values of both are a fake timestamp, to avoid the sandbox
break we formerly had by returning the real time. This is similar to how
we don't inherit OS Env values.
