Bug#908911: lintian: Allow dir-or-file-in-etc-opt to be overridable

[Jeremy Bicha <jbicha@debian.org>]

Source: lintian
Version: 2.5.103
Affects: chrome-gnome-shell

chrome-gnome-shell ships a file in /etc/opt/ [1] so that it integrates
with Google Chrome. Google Chrome installs to /opt/ and uses /etc/opt/
for configuration. Although this stirred up a bit of controversy [2]
in Debian, it seems to me like this is acceptable for Debian. (Despite
chrome-gnome-shell's name, it also integrates with Firefox and
Chromium.)

I tried to set a lintian override but it looks like this tag is listed
as non-overridable in profiles/debian/ftp-master-auto-reject.profile

According to https://bugs.debian.org/840235 it is not actually a
ftp-master autoreject any more.

[1] https://lintian.debian.org/tags/dir-or-file-in-etc-opt.html
[2] https://bugs.debian.org/888549

Thanks,
Jeremy Bicha