dco_freebsd: Add check_malloc_return after realloc

dco_freebsd: Add check_malloc_return after realloc

cppcheck complained about a potential memleak
due to realloc failure. But trying to handle that
is probably not useful. Just abort like we do
for other malloc failures.

Change-Id: Icd8ea093dfe9f1888570f3d7b786b951b5262e47
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1669
Message-Id: <20260507075321.25123-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg36842.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>