cpu/x64_64: Move MMU page table types back to <cpu/pmap.h>.

cpu/x64_64: Move MMU page table types back to <cpu/pmap.h>.

 Reduce namespace pollution.  These types are common for both
 pc64/vkernel64 and are used in pmap context only.
 All userland cases need just VM_MAX_USER_ADDRESS, PS_STRINGS constants
 through <machine/vmparam.h> with huge cpp expansion that requires
 <machine/pmap.h> header inclusion anyway.  Simplify it.

 * Hard-code NPTEPG/NPDEPG/NPDPEPG/NPML4EPG constants to properly solve
   header inclusion ordering.  The SHIFT constants are hard-coded already
   (log2() values) so there are no reasons to pretend everything will
   adjust automatically.
 * Use LU suffixes, debug printf() in vkernel64 use %ld types.
 * Optionally reorder includes in libc setproctitle.c.
 * Optionally add explicit includes in libkvm where pmap.h is only
   coming from <sys/user.h>.  The kvm_*_x86_64.c use X86_PG_* constants.

 For now keep PDESIZE/PTESIZE (used in pc64 genassym.c).

 No intermediates differences observed.