support git submodules

[virtualmarc]

support git submodules

[Haraguroicha]

This can using git submodule update --init --recursive in first line of CI settings/Scripts, but following another unofficial gitlab-ci-runner were haven't this function

[Haraguroicha]

Another way to explain, --recursive will trigger your repository to fetch submodules (older version of git), but this does not need for all repositories.
In additionally (newly version of git), using git checkout and git clone with --recursive will not effect to fetch submodules, the finally way is using git submodule update --init --recursive after checkout to initialize submodules and update recursively.

[darinkes]

Maybe you are right and doing it in the build command is a better way to go.

[virtualmarc]

Since it's not in the official runner and I don't really know how this affects the overall performance/runtime of this runner I also think it would be better as first command in the build script.