use MSG_TRUNC flag to get recv message size at once

prevent multiple calls of recvmsg.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
(cherry picked from commit d733f8a0a65a817d16ebaa1a8f5ad1330682b489)

Conflicts:
	lib/nl.c

Signed-off-by: Thomas Graf <tgraf@suug.ch>
1.1.4 release

Signed-off-by: Thomas Graf <tgraf@suug.ch>
nl: Increase receive buffer size to 4 pages

Signed-off-by: Thomas Graf <tgraf@suug.ch>