[release-branch.go1.23] cmd/compile/internal/importer: enable aliases
Flips the pkgReader.enableAlias flag to true when reading unified IR.
This was disabled while resolving #66873. This resolves the TODO to
flip it back to true.
Fixes #70394
Fixes #70517
Updates #66873
Change-Id: Ifd52b0f9510d6bcf151de1c9a18d71ab548c14e4
Reviewed-on: https://go-review.googlesource.com/c/go/+/604099
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
(cherry picked from commit
209ed1a9c75d17046285c416b74a14bb89799757)
Reviewed-on: https://go-review.googlesource.com/c/go/+/631855
Commit-Queue: Tim King <taking@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>