dnsmasq: Create rDNS records for LuCI "Hostnames"

dnsmasq: Create rDNS records for LuCI "Hostnames"

LuCI creates "domain" UCI config sections, which the dnsmasq init file
then, currently, translates into "address" config lines. This is not
the correct usage of "address" (see r36943), and also causes rDNS
records to not be created. This patches dnsmasq.init to utilize the
additional hosts file introduced in r40799 for such domain names,
resolving both issues.

Signed-off-by: Tyler Fenby <tylerf@securecominc.com>
Backport of r42318

SVN-Revision: 42388