runtime: allow proflock and mheap.speciallock above globalAlloc.mutex

runtime: allow proflock and mheap.speciallock above globalAlloc.mutex

During schedinit, these may occur in:

mProf_Malloc
  stkbucket
    newBucket
      persistentalloc
        persistentalloc1

mProf_Malloc
  setprofilebucket
    fixalloc.alloc
      persistentalloc
        persistentalloc1

These seem to be legitimate lock orderings.

Additionally, mheap.speciallock had a defined rank, but it was never
actually used. That is fixed now.

Updates #38474

Change-Id: I0f6e981852eac66dafb72159f426476509620a65
Reviewed-on: https://go-review.googlesource.com/c/go/+/228786
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>