Fixes to automate.py (issue #1067):
- 'update_depot_tools' command fails on Linux without depot_tools in the PATH.
- Always generates build log files without looking at --build-log-file.

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk@1449 5089003a-bbd8-11dd-ad1f-f1f9622dbc98