Integrate config/set_timebase

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Commit: config@dbe817a3

git-describe: remove file

Functionality of the file has been moved into distro-info.inc

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Commit: config@157dd06d

setup-environment: use distro-info.inc and set default timestamp

Include the new distro-info.inc file. Add functionality to get timestamp of
latest tag. Set that timestamp as default for the build.

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Commit: config@d89a5ea6

config: add distro-info.inc

Add git log function to get timestamp of tag, merge with the git-describe.inc file into distro-info.inc