Fix a build failure where recvmmsg is available but not sendmmsg

Fix a build failure where recvmmsg is available but not sendmmsg

Some old glibc versions have recvmmsg but not sendmmsg. We require both to
use that functionality. Introduce a test to check we have a sufficiently
recent version of glibc.

Fixes #22021

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
(Merged from https://github.com/openssl/openssl/pull/22036)