Use idiomatic slicing operations instead of incrementally building a
linked list.

Passes toolstash -cmp.

Change-Id: Idb0e40c7b4d7d1110d23828afa8ae1d157ba905f
Reviewed-on: https://go-review.googlesource.com/20556Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>