osmo-ttcn3-hacks: Add automatic management of titan dependencies to Makefiles
Currently the 'make deps-update' target must be invoked manually to update git repositories stored beneath the deps/ directory.
The build process would be more convenient and less error-prone if this were automated.
A related problem is that we are always pulling the master reference, which means our ttcn3 tests could be affected by changes made independently at eclipse.org.
The Makefiles should keep track of the exact commit hash (or a tag, if available) which should be retrieved, and update repositories under deps/ accordingly.
The mechanism should also be able to cope with changes to the remote URL of a dependency's git repository.
This might be a good use case for git submodules, but custom Makefile logic should also be able to maintain repositories in sync with the desired state.