go.tools/godoc/analysis: convert path to url (fixes windows build)
go.tools/godoc/analysis: convert path to url (fixes windows build)

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/94440043

josharian/tools,maddyonline/tools,matryer/tools,magiccao/tools,springning/tools,runcom/tools,runcom/tools,4ad/tools,golang/tools,nicot/tools,cw2018/tools,matryer/tools,argandas/tools,nicot/tools,cw2018/tools,syreclabs/go-tools,magiccao/tools,sshetty10/tools,argandas/tools,syreclabs/go-tools,glasser/golang-tools,maddyonline/tools,dmitris/tools,magiccao/tools,syreclabs/go-tools,dmitris/tools,glasser/golang-tools,cmars/tools,cw2018/tools,sshetty10/tools,maddyonline/tools,dmitris/tools,cw2018/tools,josharian/tools,jdhenke/tools,golang/tools,dmitris/tools,golang/tools,jdhenke/tools,golang/tools,springning/tools,syreclabs/go-tools,josharian/tools,4ad/tools,nicot/tools,maddyonline/tools,syreclabs/go-tools,argandas/tools,nicot/tools,josharian/tools,cmars/tools,sshetty10/tools,glasser/golang-tools,matryer/tools,jdhenke/tools,cmars/tools,springning/tools,jdhenke/tools,cmars/tools,golang/tools,sshetty10/tools,runcom/tools,springning/tools,runcom/tools,4ad/tools,argandas/tools,magiccao/tools,syreclabs/go-tools,glasser/golang-tools,matryer/tools