This will be used by Testman.
Previously, it had to translate the short hash from the build number to a long hash, but such a database (GitInfo) only exists for commits in the master branch.
- REVISION is now something like "0.4.7-dev-53-g1304b53" instead of "r12345".
- Change WINDOWS_NT_BANNER to better represent the ReactOS version and the reported NT version.
- Introduce REACTOS_COMMIT_HASH which contains the full 40-character commit hash (for comparing revisions, e.g. in rosautotest/testman).