Turn off the dvdrom target by default.  dvd1.iso is now built by
specifying 'WITH_DVD=1' during 'make release'.

This caused some problems during the freebsd-update builds for
10.0-BETA4.

MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Fix PKG_ABI detection in bsdconfig(8) after pkg-1.2 is released, since
the format of 'pkg -vv' output has changed.

MFC after:	3 days
Sponsored by:	The FreeBSD Foundation