Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC r264933:
Fix indentation in make-memstick.sh.

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

Use UFS labels and bsdlabels (like the 8.x memsticks) instead of GPT to
fix problems with some BIOSes.

MFC after: 3 days

Mount memsticks read-only by default to prevent them being filled by
user modifications and subsequently preventing a functioning installation.

Approved by: re (kib)

Use labels to find release media instead of hard-coded device paths. This
makes booting more reliable (and working at all on USB sticks). While here,
move responsibility for setting up fstab into the various platform mk-*.sh
scripts.

Suggested by: many

Add generation of memstick images to the bsdinstall release makefile for
i386 and amd64. This involved moving the memstick generation script to
the arch directories from scripts/, in analogy to mkisoimages.sh. This
script was never called from /usr/src/release/Makefile, so that hasn't
been updated.

Provide a script that can be used to create the memstick images. For now
it isn't being integrated into 'make release' because for the forseeable
future the memstick images will be identical to what's on the DVD except
for which package set is provided. If/when what's on the memstick diverges
from what's on the DVD it would make more sense to generate a "memstick"
directory in $CHROOT/R/cdrom and build the memstick image along with the
ISO images.

Reviewed by: jhb, ru, Garrett Cooper (yanefbsd at gmail dot com)