Indent the temporary file source code embedded in go_test.go, so that
we don't have temporary Go code in the first column.

No real changes to the tests, just formatting.

Change-Id: I416b4a812c8db452ea61afe63a00989ec598c228
Reviewed-on: https://go-review.googlesource.com/10926Reviewed-by: Russ Cox <rsc@golang.org>