more regen for complex and more.
this doesn't need <execinfo.h>, which doesn't exist on older hosts.
Make IPV4 mapped addresses able to do IPV4 multicast. Fixes needed:

	- allow binding to mapped v4 multicast addresses
	- define v4moptions, allow setting it via ioctl, pass it to ip_output,
	  free it when killing the pcb.

Ideally we would allow the IPV6 multicast setsockopts work on mapped addresses
too, but this is a lot more work and linux does not do it either.