gnulib: switch to use https:// instead of git:// protocol
gnulib: switch to use https:// instead of git:// protocol

Some contributors are behind obnoxious firewalls that block everything
except http(s) traffic, preventing checkout of modules using the git://
protocol. Since git.savannah.gnu.org is using the modern, fast HTTP
transport, there's no real downside to using that by default.

Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

eskultety/libvirt,olafhering/libvirt,crobinso/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jardasgit/libvirt,andreabolognani/libvirt,jfehlig/libvirt,libvirt/libvirt,eskultety/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,zippy2/libvirt,nertpinx/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,jfehlig/libvirt,nertpinx/libvirt,zippy2/libvirt,zippy2/libvirt,olafhering/libvirt,andreabolognani/libvirt,jardasgit/libvirt,crobinso/libvirt,eskultety/libvirt,libvirt/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,eskultety/libvirt,zippy2/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jardasgit/libvirt,nertpinx/libvirt,jardasgit/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,jfehlig/libvirt,eskultety/libvirt,nertpinx/libvirt