dsp: Remove generated starch code from source control

[gtjoseph]

It's tough to rebase if two people regenerate the code in
dsp/generated and commit it.

• Removed dsp/generated from source control
• Added dsp/generated to .gitignore
• Modified dsp/starchgen.py to automatically create
  dsp/generated if it doesn't exist.
• Updated Makefile to automatically run starchgen.py if
  dsp/generated/makefile.$(STARCH_MIX) is missing or out
  of date with respect to starchgen.py.

[mutability]

Part of the original design philosophies of starch was "zero build-time code generation", so regenerating on build fundamentally breaks that and means there's extra build-time dependencies (python3 and mako) - which is going to break a whole lot of downstream build scripts.

But I do appreciate the difficulty it causes for developers working with the starch code. (Which is currently a set of .. two?)

Do you have another approach that avoids the extra dependencies for a simple "I checked the code out of github and tried to build it" build.

[gtjoseph]

But I do appreciate the difficulty it causes for developers working with the starch code. (Which is currently a set of .. two?)

Heh, yeah I know. :)

Do you have another approach that avoids the extra dependencies for a simple "I checked the code out of github and tried to build it" build.

None that wouldn't make more work for us. No worries. I was just a bit annoyed when I did a rebase yesterday and all of the generated files had conflicts. I'm over it now. :)

[mutability]

No worries. If you do find something that makes things easier here while keeping the build simple, let me know your ideas