package/dnsmasq: bump version to 2.84

Bugfix release, fixing a regression introduced in 2.83.  For more details,
see the announcement:

http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q1/014640.html



Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 8fcdd202)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>