Reminder: Upstream overlay

[RobbieBuxton]

I used an overlay to fix the issue of dlib not actually building with cuda, I should upstream this so everyone can use the cuda version.

[RobbieBuxton]

Done here: https://github.com/RobbieBuxton/VolumetricSim/blob/a039420a0208ef4c56e47e8decfb9f476ab24468/flake.nix#L20

[RobbieBuxton]

Also change openblas to blas in upstream so easier to override, also fftw isn't used.

[RobbieBuxton]

https://github.com/davisking/dlib/blob/b0f6be80587b94585949f6943a7ee263394c2d15/docs/docs/release_notes.xml#L1280-L1309 FFTW is actually disabled since 2015