Log Message:
net/quagga: Expand ip_mreq hack conftest to DragonFly

DragonFly can't support the Multicast API so in order for quagga to build
the conftest for ip_mreq needs to return positive for all versions of
DragonFly.  The configure script was patched, but this probably could
have been accomplished by overriding the configure cache from the
Maefile.  DragonFly successfully buids with this conftest change.