Simplify pinning Libretro cores
To save us, maintainers, time every 6 months, we should have a way to automatically pin Libretro modules to their current HEAD version, or at least to get their ID so we can easily update it.
A somewhat dirty solution to get the current HEAD commit ID is to do something like this:
$ mkdir tmp_dir
$ cd tmp_dir
$ git init
$ git fetch --depth 1 https://github.com/libretro/bsnes-mercury.git master
$ git show FETCH_HEAD | head -n 1
> commit 4e221df676ffc7b46d083cf2ae100131eabe5076
$ git fetch --depth 1 https://github.com/libretro/beetle-pce-fast-libretro master
$ git show FETCH_HEAD | head -n 1
> commit 6dfaf04cf2085ab9e5bb6ffac75070816cb4ff52
$ cd ..
$ rm -rf tmp_dir
Edited by Adrien Plazas