built_in: changed to use RUNTIME_PAGE_SIZE instead of PAGE_SIZE

References:

https://github.com/netsniff-ng/netsniff-ng/commit/453f6eb9d79dd5aa2812ef956b22723f0a493086
https://github.com/netsniff-ng/netsniff-ng/pull/112

Signed-off-by: Christian Wiese <chris@opensde.org>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
built_in: changed RUNTIME_PAGE_SIZE to use sysconf(_SC_PAGE_SIZE) instead of getpagesize()

getpagesize(2) is considered legacy and has been dropped with POSIX.1-2001.

See discussion: https://github.com/netsniff-ng/netsniff-ng/pull/112

Signed-off-by: Christian Wiese <chris@opensde.org>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>