build: add detection of xdrproc_t arguments count

build: add detection of xdrproc_t arguments count

According to 9fa3a8ab6fd82ad2f5a14b490696085061418718,
macOS insists on passing 3 arguments for xdrproc_t.

Passing 3 arguments was a good common ground, but since
recently[1] FreeBSD only accepts 2 arguments.

Add a meson.build check whether 3 arguments are accepted,
and add macros which passes either 2 or 3 arguments to
xdrproc_t based on the result of this check.

1: https://cgit.freebsd.org/src/commit/?id=ac5a19ec6989675c8ec6c3ca245dba243d1a6416

Signed-off-by: Roman Bogorodskiy <bogorodskiy@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>