More x86-64 updates for 2.5.54.  Most noticeable change is that the
64bit X server works again.

This only changes x86-64 specific files.  It requires some AGP driver
changes I'm sending separately.

 - Some Makefile cleanups from Sam Ravnborg
 - Make sure extended registers in 32bit processes are zeroed and not
   accessible/changeable from ptrace.  This is to avoid potential
   security bugs with non 64bit clean 32bit emulation functions (they
   often are overflow prone etc.)
 - Some 32bit emulation cleanups from Stephen Rothwell
 - Make copy_*_user source const to fix warnings.
 - Set fs/gs to dummy values when the 64bit segment base is set to not
   confuse the context switch (Karsten Keil, me)
	* still one mysterious bug in this area unfortunately.
 - Make MAP_32BIT for 64bit processes only map in the first 31bit,
   because it is usually used to map small model code.  This fixes the X
   server crashes.  Some cleanups in this area.
 - Don't set O_LARGEFILE for 32bit open
 - Handle ptregs calls from 32bit syscall correctly.
 - Implement aio io_getevents for 32bit.
 - Remove buggy unused command handler in nfsd 32bit emulation.
 - Convert timespec in semtimedop (thanks to Anton for telling me about
   this)
 - Ignore long mode flag from 32bit modify_ldt.  This fixes Wine, which
   left it uninitialized (bug found by Karsten Keil)
 - Merge with i386
 - Handle new kallsyms
 - Remove some superfluous bootup printks