libxl: build, check and pass vNUMA info to Xen for PV guest

libxl: build, check and pass vNUMA info to Xen for PV guest

Transform the user supplied vNUMA configuration into libxl internal
representations, and finally libxc representations. Check validity of
the configuration along the line.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Elena Ufimtseva <ufimtseva@gmail.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>