buildroot

package/waf: new host package

host-waf will be used by waf-based packages that do not include it in
their release tarballs, like mpv.

mpv is currently the only case we have, but with the upcoming
waf-package infra, having host-waf available just makes the infra
complete from the onset.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Romain Naour <romain.naour@openwide.fr>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
[Thomas: drop dependency on host-python, it's really a runtime dependency.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>