Tweak deprecation message so Haddock recognizes module name

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Change exit code encoding of `waitForProcess` yet again

This changes the exit code encoding from `(128+signum)`
(as introduced via 5403824028) to

{{{#!hs
if coredump then 0x8000 else 0 .|. signum `shiftL` 8 .|. exitstatus
}}}

in order to address the `process`-package part of #7229

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>