cmd/link: ignore "operation not permitted" fallocate errors.

cmd/link: ignore "operation not permitted" fallocate errors.

Ignore an additional class of errors form fallocate, falling back to
heap allocated buffers for output.

Fixes #41356

Change-Id: Iaaa91620cec644c78978e0b258f166bc204a3f85
Reviewed-on: https://go-review.googlesource.com/c/go/+/254777
Trust: Jeremy Faller <jeremy@golang.org>
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>