[dev.typeparams] cmd/compile: change export version to 1.17 for testing

This is a temporary change. We will revert this back before the 1.18
release. We make this change now to simplify testing, since a lot of
tools will break on the new export version.

Updates #47654.

Change-Id: I0650fa753bb11229c71254d779dd61b5c1af9cdf
Reviewed-on: https://go-review.googlesource.com/c/go/+/341211


Trust: Dan Scales <danscales@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>