Check previously-unchecked buf_alloc_write() call in crypto self-test.

Check previously-unchecked buf_alloc_write() call in crypto self-test.

"It cannot be NULL", but since this is self-test infrastructure, assume
the worst - add ASSERT() check to ensure assumptions are true.

Found by Coverity.

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <1478596632-22842-1-git-send-email-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg12940.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>