mbox: Handle CFWS comments
mbox: Handle CFWS comments

This example header is standard compliant but not handled correctly:

In-Reply-To: <20170509173559.31598-4-marcandre.lureau@redhat.com>
      (=?utf-8?Q?=22Marc-Andr=C3=A9?=
      Lureau"'s message of "Tue, 9 May 2017 20:35:45 +0300")

The grammar:

    in-reply-to     =       "In-Reply-To:" 1*msg-id CRLF

    msg-id          =       [CFWS] "<" id-left "@" id-right ">" [CFWS]

    then looking at 3.2.3 on folding white space and comments:

    CFWS            =       *([FWS] comment) (([FWS] comment) / FWS)

    comment         =       "(" *([FWS] ccontent) [FWS] ")"

Signed-off-by: Fam Zheng <df9fd617995bad07eac70e27aa3fe5069270e3bd@redhat.com>

pvital/patchew,pvital/patchew,pvital/patchew,pvital/patchew