Cross compile docker should mount /leosac volume read only

[xaqq]

The cli cc.py mount the leosac volume rw to fix a build issue.

The build should be fixed and the cc.py tool should mount the volume read-only.
The issue is: odb schema files are generated in the source tree.

[knight-of-ni]

Thank you. That fixed the very issue I was staring at this afternoon.