Remove FRAME_HEADROOM, PAYLOAD_SIZE, EXTRA_FRAME and TUN_LINK_DELTA macros

Remove FRAME_HEADROOM, PAYLOAD_SIZE, EXTRA_FRAME and TUN_LINK_DELTA macros

The buffer overhaul simplified the frame struct to a point that these
macros are either not used anymore or are not adding any benefit in
understanding the code anymore. Replace the macros with direct member
acessses.

Patch v2: Remove all FRAME_HEADROOM macros
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20220214092607.3785665-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23785.html

Signed-off-by: Gert Doering <gert@greenie.muc.de>