<sys/types.h>: Reduce vm_* types pollution in userland.

<sys/types.h>: Reduce vm_* types pollution in userland.

 Userland should not be using these types outside kernel structures or
 <vm/*.h> scope.  Adjust several userland and boot code sources to
 include <machine/types.h> where they use them (mainly for vm_offset_t).
 * sys/fbio.h: Used in several world utilities and libvgl.
 * sys/kinfo.h: Use size_t for kp_vm_map_size (header used in userland).
 * sys/emulation/ndis/pe_var.h: Used in ndiscvt(8).
 * bus/firewire/fwcrom.c: Compiled directly in fwcontrol(8).
 * mptable(1): include <machine/types.h>, should really not be using
   vm_offset_t and looks to be suspiciously broken.
 * sys/boot: For now include <machine/types.h> for vm_offset_t in
   several headers, should really not be using vm types.

 Rest of world utilities get vm types through <sys/user.h>.

 While there, move pthread type inclusion to the very end of the source,
 doing so improves readability of compiler intermediates a lot.

 Strictly visibility changes only.