This commit adapts TestStmtLines for AIX operating system.

Update #25893

Change-Id: I1c76bbd8fc679a66b65ecfbd1ed7745518064eae
Reviewed-on: https://go-review.googlesource.com/c/144958Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>