envsetup.sh: take control of defining OUT_DIR and DIST_DIR

Delegate calculation of OUT_DIR and DIST_DIR to envsetup.sh. That way it
can be reused for other scripts like build.sh.
Also ensure that envsetup.sh is only included once.

Change-Id: Ie61b8b6bc2ac10d31302a0e161748899c7463496
Signed-off-by: Matthias Maennich <maennich@google.com>
2 files changed