compiler: don't set ptrmask bit for pointer to notinheap type
compiler: don't set ptrmask bit for pointer to notinheap type

Test case is https://go.dev/cl/385454.

Change-Id: I9f84476b1884d66aae2c673297f47a877f60ef58
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/385474
Trust: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Reviewed-by: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>

golang/gofrontend,golang/gofrontend,golang/gofrontend,golang/gofrontend