[sdiy] Some Audio DSP prototypes

[Eric Brombaugh]

I've posted the current status of my Clang efforts on github here:

https://github.com/emeb/f303k8_nucleo

That includes a complete STM32F303k8 project with makefile that can be 
configured for either GCC or Clang. The GCC build flashes and runs 
properly, the Clang one builds but does not flash. I've also included 
the .map and .dmp files from the linker process in each case for anyone 
who understands that sort of thing. If wiser eyes than mine can find an 
obvious error I'd appreciate hearing about it.

Eric