toolchain_util: build stable cross gdb, misc cleanups
setup_board: setup gdb wrapper and debug symbol path
make_chroot: don't enable git-prompt via bashcomp

Newer git ebuilds have decided that the "git-prompt" script isn't really
bash completion so stopped installing it via that mechanism. Instead it
installed it started installing it in /usr/share/docs which gets
compressed by default and the path is based on ebuild version. The path
changed again in 1.9.3 to /usr/share/git and didn't compress it so that
makes it actually possibly usable but 1.9.3 or later isn't stable yet.

We can re-enable it the next time git gets updated but not worth fussing
over the current brokenness right now.
Merge pull request #316 from marineam/git

make_chroot: don't enable git-prompt via bashcomp
Merge pull request #315 from marineam/gdb

Setup GDB in the SDK
toolchain_util: fix bash syntax when running as root

Apparently expanding an empty string before a variable assignment forces
that assignment to be interpreted as a command instead. Instead of an
empty string use env as our sudo alternative when running as root.
Merge pull request #317 from marineam/sudo

toolchain_util: fix bash syntax when running as root
chroot: remove git from $PS1

This feature is disabled for now. See c8a62a12 for details.
Merge pull request #319 from marineam/git

chroot: remove git from $PS1
image_set_group: copy contents and packages text files
Merge pull request #320 from marineam/packages

image_set_group: copy contents and packages text files
rename references to updatectl, it is now updateservicectl
Merge pull request #321 from marineam/updatectl

rename references to updatectl, it is now updateservicectl
digitalocean: Add image format for digitalocean