tools/libxc: drop xc_map_foreign_bulk_compat wrappers

tools/libxc: drop xc_map_foreign_bulk_compat wrappers

On Solaris and NetBSD xc_map_foreign_bulk is implemented by calling
xc_map_foreign_bulk_compat and xc_map_foreign_bulk_compat is exposed
as a symbol by libxenctrl.so.

Remove these wrappers and turn the compat function into the real thing
surrounded by the appropriate ifdef.

As this is a compat function all new ports should instead implement
xc_map_foreign_bulk properly, hence the ifdef should never be
expanded.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>