runtime: record synctest bubble ownership in hchan
Replace the hchan.synctest bool with an hchan.bubble reference
to the synctest bubble that created the chan. I originally used
a bool to avoid increasing the size of hchan, but we have space
in hchan's current size class for another pointer.
This lets us detect one bubble operating on a chan created
in a different bubble.
For #67434
Change-Id: If6cf9ffcb372fe7fb3f8f4ef27b664848578ba5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/674515
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Damien Neil <dneil@google.com>