runtime: call enableMetadataHugePages and its callees on the systemstack
These functions acquire the heap lock. If they're not called on the
systemstack, a stack growth could cause a self-deadlock since stack
growth may allocate memory from the page heap.
This has been a problem for a while. If this is what's plaguing the
ppc64 port right now, it's very surprising (and probably just
coincidental) that it's showing up now.
For #64050.
For #64062.
Fixes #64067.
Change-Id: I2b95dc134d17be63b9fe8f7a3370fe5b5438682f
Reviewed-on: https://go-review.googlesource.com/c/go/+/541635
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Paul Murphy <murp@ibm.com>