Don't run packet_id unit tests for --disable-crypto builds

Don't run packet_id unit tests for --disable-crypto builds

Because there is no packet_id in those builds...  This fixes 'make check'
for --disable-crypto builds, caught by travis.

Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <1494014848-20099-1-git-send-email-steffan.karger@fox-it.com>
URL: http://www.mail-archive.com/search?l=mid&q=1494014848-20099-1-git-send-email-steffan.karger@fox-it.com
Signed-off-by: David Sommerseth <davids@openvpn.net>
(cherry picked from commit dcfcc594759b3a768cd4d40508cbacae114c274b)