Update dnsmasq-devel to 2.81rc1.
This currently adds two portability fixes that have been reported upstream.
Changelog: http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=blob;f=CHANGELOG;h=31b395c987fe50174533065afe816dec3d4284a1;hb=b2ed691eb3ca6488a8878f5f3dd950a07b14a9db#l1