When enabled, it writes out a chrome trace file populated with events from the YARN_* event macros.

Bug: b/139010488
Change-Id: Ifae27b2bcf08f767e9886664b1a998162a617108
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/34813Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>