Add accumulated bug fixes for x86-64 and some minor cleanups.

 - Add ptep_set_access_flags from i386
 - Change memory text mapping to 10MB from 40MB to make alias window
   smaller
 - Disable change_page_attr for kernel mapoing for now (wrong, but the
   other code also doesn't work)
 - Add .bss.page_aligned and align interrupt/exception stacks (idea from
   Matt Mackall)
 - Protect sysenter MSR setup against missing registers. 
 - Set mce tolerance level to 1 (panic instead of deadlock)
 - Fix cross 4GB bug in find_first_bit (Michael Matz)
 - Add missing memory clobbers in bitops.h (Suresh B.  Siddha)
 - Check kernel size at boot up
 - Set boot cpu online at boot to fix early printk
 - Fix EFER bit definitions (Dave Jones)
 - Fix comments in 32bit syscall table.
 - Quieten all 32bit syscalls that are unimplemented in 32bit. 
 - Various MCE fixes suggested by Eric Morton, David Boles et.al.
   More to come.
 - Quieten some printks
 - Fix cpu online check in msr driver
 - Lower polling interval for machine checks to 5 minutes to avoid
   overrunning the registers. 
 - Make memcpy_{from,to}io more compatible with i386 (Roland Dreier)