build : start using a ggml submodule

[ggerganov]

Currently, the ggml source tree is synchronized into the source tree of whisper.cpp:

https://github.com/ggerganov/whisper.cpp/tree/master/ggml

This is not ideal, because the ggml source code is duplicated and has to be synchronized regularly via manual process. Instead, the ggml source should be available as a git submodule.

• Reorganize this repo to start using ggml as a git submodule
• Update documentation and build instructions
• Add support for linking against external ggml binaries

[mkmkme]

Hey! I've never worked with whisper.cpp, but I find the project interesting. This task seems very easy, so if nobody takes it I can handle it later today.

[ggerganov]

Thanks for the interest. Just to set the expectations correctly - none of the tasks in the new roadmap are really difficult from technical perspective, but they do require some level of commitment and familiarity with the project and it's intricacies. Such changes to the whisper.cpp build process would require good documentation, communication with developers and handling any issues that would arise from this change.

[WilliamTambellini]

superb @ggerganov