This refactors the benchmarks to use static functions which support
passing arbitrary arguments, instead of fixtures:
https://github.com/google/benchmark#passing-arbitrary-arguments-to-a-benchmark

This makes it easier to have a variant with and without multisampling,
and avoids using state.counters[] as a hack to display clear formats.

Bug: b/158231104
Change-Id: Icf0eed254dc942af8f2bcfc975a1e5e581b6e786
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/45790
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>