This is a preliminary patch to paravirtualizing fsys.S.
compile fsys.S twice one for native and one for xen, and switch
them at run tine.
Later fsys.S will be paravirtualized.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>