Stabilise unix_process_await_more, extra ExitStatusExt methods
Stabilise unix_process_await_more, extra ExitStatusExt methods

Signed-off-by: Ian Jackson <d68d4287c1430ca128ad85033356c9d259238c74@chiark.greenend.org.uk>

graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust