cmd/getgo: fix build on aix
cmd/getgo: fix build on aix

Change-Id: Ic4a2f8f32258b14354658af5a09c736404d38808
Reviewed-on: https://go-review.googlesource.com/c/tools/+/170961
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools