Remove a stray debugging printout when running on Xen.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Xen HVM when used with the "vmxassist" program crashes if HLT is
executed in real mode.  Detect a version of Xen old enough to support
"vmxassist", and if it is found, then disable HLT.

See: https://bugzilla.redhat.com/show_bug.cgi?id=570496

Reported-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

We haven't enabled DO_WBINVD for a very long time.  A20 is implemented
on the inside of the L1 cache for 486+ (and 386 didn't have WBINVD),
so an I/O delay is the only thing we can rely on anyway.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Impact: major restructuring

New shuffler routine which runs entirely in protected mode, unlike the
old one which would enter PM for the bcopy phase only.  This is not
only faster, but it greatly reduces the size of the shuffler "critical
area".  The interfaces to this new shuffler are not yet implemented,
so this is a non-functional checkpoint.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Mechanically rename the writestr functions:

	writestr   -> writestr_early
	cwritestr  -> writestr

... to reflect which function is more appropriate to call in normal
circumstances.

Move source files out of the root directory; the root is a mess and
has become virtually unmaintainable.  The Syslinux core now lives in
core/; the Linux and generic utilities has moved into utils/, and
copybs.com has moved into dos/; it had to go somewhere, and it seemed
as good a place as any.