whisper : support GGML_BACKEND_DL

[slaren]

No description provided.

[slaren]

I didn't notice any issues with the basic functionality, but I am not sure how to test the DTW stuff. The CI failures seem unrelated.

[ggerganov]

The DTW feature hasn't been exercised for a long time and it seems it broke at some point. The original command that used to work when the feature was added was:

./main -m models/ggml-small.bin -f samples/gb0.wav -dtw small -ojf

#1485 (comment)

Pinging @denersc if they can take a look after merging. But I think it is not super important, since the feature is marked as experimental anyway and I am not sure if it got any significant usage.

[slaren]

I had introduced issues in the DTW code, but it should be fixed now.

The ios-xcode-build CI is failing, it looks like that's because I added the ggml-cpp.h header in whisper.cpp, and it has its own build system, but I don't know how to fix that. It would be easy to remove this header if necessary, it's not used for anything important.

The Ruby CI is also failing, but don't know why or if it is related to the changes here.

[ggerganov]

I am not sure why the Ruby workflow is failing too, but it's ok to ignore for now. @KitaitiMakoto will probably take a look later.