Revert "Multi-threaded strike cache"

This reverts commit a6cd7c0b1f989840efe203979943cbb59d4d131b.

Reason for revert: Introduced nullptr de-ref in last patch

Original change's description:
> Multi-threaded strike cache
> 
> Allow multiple threads to share the same strike. The old
> system of removing the cache from the linked list is no longer.
> The strikes stay in the list and can be found by other threads.
> 
> * Removed strike size verification. There was no way to get the
> locks to work out. The whole point of the change was to have multiple
> threads muting the structure at the same time.
> 
> * Strikes are now refed instead of being checked out. Therefore,
> ExclusiveStrikePtr is now just wraps an sk_sp, and should be renamed
> in a future CL.
> 
> Change-Id: I832642332a3106e30745f9cdd3156ae72d41fd0b
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/272057
> Reviewed-by: Ben Wagner <bungeman@google.com>
> Commit-Queue: Herb Derby <herb@google.com>

TBR=bungeman@google.com,herb@google.com

Change-Id: Ie1acd9b42e614c17cb63bda1b3fd4dd9827a8fa6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/272378
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Herb Derby <herb@google.com>
5 files changed