mailinfo: better parse email adresses containg parentheses

mailinfo: better parse email adresses containg parentheses

When using git-rebase, author fields containing a ')' at the last position
had the close-parens character removed; the removal should be done only
when it is of this form:

        user@host (User Name)

i.e. the remainder after stripping the e-mail address part is enclosed in
a parentheses pair as a whole, not for addresses like this:

        User Name (me) <redacted>

Signed-off-by: Philippe Bruhat (BooK) <redacted>
Acked-by: Lukas Sandström <redacted>
Signed-off-by: Junio C Hamano <redacted>