Do not strip all when stripping an explicit symbol

When requested to strip specific symbols (-N flag) the default should be
to strip nothing (other than the requested symbols). This is consistent
with binutils strip(1).

PR:		196038
Reviewed by:	imp
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D1327
Make sequence numbers checks more strict.

While we don't support MCS, hole in received sequence numbers may mean
only PDU loss.  While we don't support lost PDU recovery, terminate the
connection to avoid stuck commands.

While there, improve handling of sequence numbers wrap after 2^32 PDUs.

MFC after:	2 weeks