imudp: refactor in preparation of recvmmsg() enhancement
imudp: refactor to use recvmsg() in preparation for recvmmsg()
imudp: fix error message on socket error condition
imudp milestone: recvmmsg() now supported, but reads only a single msg

obviously, as an end-result that would be brainless ;)
imudp: add support for recvmmsg()
Merge branch 'c8'

Conflicts:
	configure.ac
	plugins/imudp/imudp.c