The change instruments code generation for Gap Solver so that these
counters are run-time and didn't impact register allocation.

The implementation is put behind a flag to help better register
allocation analysis.

Bug: v8:10663
Change-Id: Ia342d990e2b2bfc6a7653a770f670e51eef71312
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2269362
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#68664}