misc/cgo/testcarchive: fix test to work for gccgo

This test is not yet run, but it will be soon.

Change-Id: I7ed81a0c8da7c3e34a25ef8aa58bca164611ba16
Reviewed-on: https://go-review.googlesource.com/47038
Reviewed-by: Than McIntosh <thanm@google.com>
2 files changed