All those files are standalone programs that can be executed directly.
Some .py files were marked executable, others weren't, probably accidentally.
Mark them all as executable in preparation for subsequent changes.
It makes it easier to process the license automatically like other files.
The text of the license in tools/chromiumos/LICENSE matches
https://spdx.org/licenses/BSD-3-Clause.html exactly.
There is no change in the file right now, but the download seems to work
OK.
It's funny that the biggest company in the world cannot provide a
download link in plain text.