internal/gen: bugfix: escape the escape character

Change-Id: Ib39499508296af25c02a81aaf194b292bac17854
Reviewed-on: https://go-review.googlesource.com/30393
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed