5D3: Fix 5D3 build (#1506) and enable in Makefiles.
Created originally on Bitbucket by rufustfirefly (Jeff Buchbinder)
Changesets for this Pull Request have not been imported, because it had been already declined on Bitbucket. Marked as closed by the import user.
Fixes breaking 5D3 build, enable in build system (for some reason, even the cutting edge models appear to be supported in the main Makefile, but not 5D3).