This change fixes a regression introduced by the building the builtin
package on demand. Although this change increases the startup tasks of
gopls, it is necessary to ensure that we ignore diagnostics from
builtin.go.
Change-Id: I897e747a273056d70cecba486a74c75a736d8f80
Reviewed-on: https://go-review.googlesource.com/c/tools/+/179921
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>