Performance experiment: Disable SkSL optimization in nanobench/skpbench

Cloned from http://review.skia.org/369716
Re-running the experiment now that @switch is supported when
optimizations are disabled.

Change-Id: I428051d9c679a8084589fba428a637f36587be16
Bug: skia:11341
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/374516
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
3 files changed