Bug#970604: Missing golang.org/x files

[Shengjing Zhu <zhsj@debian.org>]

Source: gcc-10
Severity: important

These files are missing in libgo-10-dev package:
https://github.com/golang/gofrontend/tree/master/libgo/go/golang.org/x

This causes containerd FTBFS on ppc64,
https://buildd.debian.org/status/fetch.php?pkg=containerd&arch=ppc64&ver=1.4.1%7Eds1-1&stamp=1600269780&raw=0

go build golang.org/x/net/http2/hpack: no Go files in /usr/src/golang.org/x/net/http2/hpack
go build golang.org/x/net/http/httpguts: no Go files in /usr/src/golang.org/x/net/http/httpguts
go build golang.org/x/net/idna: no Go files in /usr/src/golang.org/x/net

These files are in upstream libgo repo, and
https://github.com/golang/gofrontend/blob/master/libgo/libgo-packages.txt