This change fixes two issues with VTune JIT Profiling API.

1. Update way of setting flag "--no-compact-code-space" to avoid changing flags after initialization v8.
2. Fix a crash from visiting uninitialized ptr.

Change-Id: I4878ffd554ce53630db961fe09b49e081b0091bf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3787321Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Fanchen Kong <fanchen.kong@intel.com>
Cr-Commit-Position: refs/heads/main@{#82003}