The iOS test harness only include files from the tested package or
below. Skip a test on iOS that required files outside the package.

Change-Id: Iaee7e488eb783b443f2b2b84d8be2de01227ab62
Reviewed-on: https://go-review.googlesource.com/c/144110
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Peter Weinberger <pjw@google.com>