The parallel move optimizer tries to use the scratch register to store
cycle breaks, but needs to spill the value if the scratch register is
needed for stack->stack moves. Whether this spill happened is supposed
to be tracked with the scratch_has_cycle_start_ field, but the update of
this field was missing.

Bug: v8:7700
Change-Id: I2dc8d9186c9ec8ca03104fd3ae972a38924670ed
Fixed: chromium:1364783
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3899086
Commit-Queue: Jakob Linke <jgruber@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83297}