Use one-big-switch when [[clang::musttail]] is unavailable.

This is intended to generate the exact same code as before when
SKCMS_HAS_MUSTTAIL is not enabled.

Bug: chromium:1504816
Bug: chromium:1504823
Change-Id: Ice4e25696dfd98ba3de14bad5c58c60e69f38902
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/787502
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
3 files changed