debianutils: Convert to update-alternatives.bbclass

This causes the configuration to be done at build time
rather than on first boot.  It also fixes errors in the
postinstall scripts that were not getting caught.

Submitted for upstream review and merge here:
    http://lists.openembedded.org/pipermail/openembedded-devel/2014-June/096576.html
    http://lists.openembedded.org/pipermail/openembedded-devel/2014-June/096577.html

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
Merge pull request #242 from drewmoseley/fix-debianutils

debianutils: Convert to update-alternatives.bbclass
Add distro file for mel-lite

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
setup-mel-builddir: Set distro based on environment variable if set

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
setup-mel-builddir: Disable profiling for MEL Lite.

Disable the "tools-profile" setting and oprofile package
if the DISTRO is MEL Lite.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>
archive-release: Adjust local.conf.sample for MEL Lite.

Set the EXTERNAL_TOOLCHAIN_PATH properly for MEL Lite installs.

Signed-off-by: Drew Moseley <drew_moseley@mentor.com>