The system stack is only around 8kb on ARM so one can't put an 8kb buffer on
the stack. More than 1024 ARM cores seems sufficiently unlikely for the
foreseeable future.

Fixes #11853

Change-Id: I7cb27c1250a6153f86e269c172054e9dfc218c72
Reviewed-on: https://go-review.googlesource.com/12622Reviewed-by: Austin Clements <austin@google.com>