fix const order in docs

SkColor_Reference.md and SkMatrix_Reference.md generated
different contents depending on which platform bookmaker
was built. Fixed so that generated const tables keep
the same order as was defined in the includes.

TBR=reed@google.com,herb@google.com

Docs-Preview: https://skia.org/?cl=165940
Bug: skia:
Change-Id: I69543ff365c2b1d71c4bc6052ffb3acdac990ef4
Reviewed-on: https://skia-review.googlesource.com/c/165940
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
3 files changed