This enhances the existing line number test
to allow a specific -gcflags (e.g., -G=3)
and to permit ignoring duplicate line numbers
(which is arguably a bug, but not THIS bug,
and it lowers the risk of a flaky test).
Limited to Linux/Darwin and amd64/arm64,
also tests with "unified" mangling.
And, using these new powers, adds a test.
Updates #49436.
Change-Id: I09c82e6a08d53edd5a752522a827e872d3e16e0b
Reviewed-on: https://go-review.googlesource.com/c/go/+/362714
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>