bluelog: fix oui.txt processing

bluelog: fix oui.txt processing

 - Use a temporary file path within the package build directory to avoid
   cluttering the host systems `/tmp` directory.

 - Switch to a gzipped, snapshotted copy of the `oui.txt` file since the
   upstream IEEE server is extremely slow, also fetching an unversioned HTTP
   resource during compilation breaks reproducable builds.

Signed-off-by: Jo-Philipp Wich <redacted>
[rework to use standard download facility]
Signed-off-by: Etienne CHAMPETIER <redacted>