runtime: fix lockrank ordering for pinner implementation
The new Pinner API's implementation imposes some partial-orders that are
safe but previously did not exist between a mspanSpecial, mheapSpecial,
and mheap. Fix that up in the lock ranking.
For #46787.
Change-Id: I51cc8f7f069240caeb44d749bed43515634f4814
Reviewed-on: https://go-review.googlesource.com/c/go/+/496193
Run-TryBot: Michael Knyszek <mknyszek@google.com> Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Knyszek <mknyszek@google.com>