Fix a bug in decoding string indexes in snmp_target(3), thus causing
bsnmpd(1) to not send v3 notifications properly; while here add two
missing return statements which could lead to abort() in case of a
rollback


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272878 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Restore the backed-out change, using __offsetof instead.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272880 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
For gcc 4.6 and newer, _Static_assert is a keyword, so don't try to
redefine it. It does what we want, and is always available unlike
other alternatives.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272881 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f