The test "signal_reported_right" send a signal `1` to `/bin/sh`, and check
the status code to check if the signal is reported right.
Under OpenBSD, the signal `1` (`SIGHUP`) is catched by `/bin/sh`,
resulting the test failed.
Use the uncatchable signal `9` (`SIGKILL`) for test.
Per [RFC 579](https://github.com/rust-lang/rfcs/pull/579), this commit
adds a new `std::process` module. This module is largely based on the
existing `std::old_io::process` module, but refactors the API to use
`OsStr` and other new standards set out by IO reform.
The existing module is not yet deprecated, to allow for the new API to
get a bit of testing before a mass migration to it.
