send-email: further warn about unsupported sendmail aliases features
send-email: further warn about unsupported sendmail aliases features

The sendmail aliases parser diagnoses unsupported features and
unrecognized lines. For completeness, also warn about unsupported
redirection to "/path/name" and "|command", as well as ":include:".

Signed-off-by: Eric Sunshine <8d6e34f987851aa599257d3831a1af040886842f@sunshineco.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git