MFC r271480, r271483, r271491:

r271480:
  Set PKG_CACHEDIR to an 'All/' directory one level lower
  to fix 'pkg repo' generating repository metadata for the
  on-disc packages.

r271483:
  Fix duplicate PKG_ABI in the PKG_CACHEDIR path.

r271491:
  Simplify dvd package population with pkg-1.3.

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