tools: Make vcachetuner easier to configure
tools: Make vcachetuner easier to configure

Instead of hard-coding cache/valence sizes, use named constants so that
they are easier to change. Additionally, make it so that adjusting the
profiles to optimize for just involves editing one profiles[] array.

This change also decouples crossover & mutation between cache/live
(which is sort of necessary for having different array sizes, but can
also improve the discoverability of some options) and switches the
default training options to just consider AMD GCN & NVidia Pascal.

zeux/meshoptimizer,zeux/meshoptimizer,zeux/meshoptimizer