linux(4): Fix control message size calculation again

It looks Linux recvmsg allows msg_controllen size less then CMSG_SPACE
buffer, at least for case with one cmsghdr. Glibc misc/tst-scm_rights
test succed on Ubuntu 23.04

Fixes: 67116c69 "linux(4): Fix control message size calculation"
MFC after: 1 week