- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Replace all uses of the old netgraph constants NG_*LEN by the new
constants NG_*SIZ that include the trailing NUL byte. This change
is mostly mechanical except for the replacement of a couple of snprintf()
and sprintf() calls with strlcpy.

Add build infrastructure for libbsnmp and the modules. Add the
netgraph module for the SNMP daemon.