License checking: Determine on policy regarding Speedb's license in Makefiles/CMakeLists.txt and enforce in the check-license phase

[udi-speedb]

There are several Makefile/CmakeLists.txt files in RocksDB / Speedb. Some have LevelDB and / or Facebook's license text and some don't.
We need to decide whether we add our own license to these files, and, consequently, whether to include these files in the check-license phase in GitHub.