[Ninja] Support 'llbuild ninja build --version' reporting a Ninja-compatible version number.
[Ninja] Support 'llbuild ninja build --version' reporting a Ninja-compatible version number.

 - This allows other tools to check for Ninja feature compatibility using the
   version number (e.g., for 'console' pool support).

apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild,apple/swift-llbuild