compiler: remove range-based 'for' loop

Fix for GCC PR/90669: remove range-based 'for' loop to preserve
buildability with g++ version 4.X.

Change-Id: Idf1e2da007b3d68f9ffa824622060ad01d29f0ab
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/179397
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed