Add a flag to control deb-srcs and only add host bins to the chroot if the distro matches.
Add a flag to control deb-srcs and only add host bins to the chroot if the distro matches.

This fixes a problem on the Chrome buildbots where installing a hardy32 chroot
on a lucid64 machine results in 'ld' and other files in the chroot which do not
work because glibc is too old, and also prevents problems with apt-get fetching
from custom mirrors without source packages.

Review URL: http://codereview.chromium.org/3797014

git-svn-id: http://src.chromium.org/svn/trunk/src@63175 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 91bdf88e05505eedd5905b694e0f50dada22839c
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser