pkg add: PKG_FLAG_FORCE->PKG_ADD_FORCE: this is not a job flag, but a flag for add.c to get
ssh -p <port>, not -P
Merge pull request #789 from skinder/master

pkg add: PKG_FLAG_FORCE->PKG_ADD_FORCE
Update docco on how to build from source to reflect the new autotools
reality.

Fixes #788
Merge branch 'master' of github.com:freebsd/pkg
Fix repos without signatures support.
Use the PORTSDIR config variable when generating ports INDEX output,
rather than hardwiring '/usr/ports' into the code.  All the world is
not FreeBSD and ports can be elsewhere on different systems.
Document the -I option, a shorthand <query-format> used to generate
ports INDEX lines.
Sync the pkg.conf.sample with the currently allowed list of
configuration variables.