MFC r259426, r259427:

MFC r259426, r259427:

r259426:
  Add a pkg(8) repository configuration file for cdrom-based package
  installation.

  As part of the 'pkg-stage' target, copy the configuration file
  to the 'packages/repos/' directory on the DVD filesystem.

r259427:
  Export 'REPOS_DIR' when the selected source medium for package
  installation is cdrom.  This enables bsdconfig(8) to make use
  of the on-disc pkg(8) repository configuration, which fixes
  package selection and installation from the dvd installer.

Approved by:	re (delphij, glebius)
Sponsored by:	The FreeBSD Foundation

git-svn-id: svn://svn.freebsd.org/base/releng/10.0@259534 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f