FC4 release 1290 build fails with ARCH=xen

[Jeffrey Buell]

The regular FC4 release 1290 build is fine on my i686 box, but building with
ARCH=xen (with the xen0 config file included with the source) fails.  The
file asm/synch_bitops.h does not exist but is needed by asm-xen/evtchn.h.
Similarly, asm/hypercall.h does not exist but is needed by
asm-xen/hypervisor.h.  Header files with these names are in asm-xen/asm-i386
but using these leads to compile errors involving the structs evtchn_op_t and
physdev_op_t.  Is this a known problem and are there any workarounds?  The
only change I made was to remove SOURCES/kernel-2.6.11-i586-smp.config in
order to get rpmbuild to work.

Jeff