html: remove license references from benchmark test data
html: remove license references from benchmark test data

The license references puzzle programs that grep for licenses.

Fixes golang/go#13573.

Change-Id: I601fbc6ba2b189b476af1082c48fb02cd72f59d8
Reviewed-on: https://go-review.googlesource.com/17714
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

cesanta/goxnet,cesanta/goxnet,albertjin/golang-net,cmars/tools,DramaFever/golang.org-x-net,cmars/tools,DramaFever/golang.org-x-net,cmars/tools,albertjin/golang-net,cmars/tools,golang/net