* config/i386/tm-i386sco5.h: Include "i386/tm-i386v4.h" instead of

* config/i386/tm-i386sco5.h: Include "i386/tm-i386v4.h" instead of
"i386/tm-i386.h", "i386/tm-i386v.h" and "config/tm-sysv.h".
Adjust a few comments to reflect reality a bit closer.
(KERNEL_U_SIZE, TARGET_HAS_HARDWARE_WATCHPOINTS,
TARGET_CAN_USE_HARDWARE_WATCHPOINT, HAVE_CONTINUEABLE_WATCHPOINT,
HAVE_STEPPABLE_WATCHPOINT, STOPPED_BY_WATCHPOINT,
target_insert_watchpoint, target_remove_watchpoint):
Move defines to ...
* config/i386/nm-i386sco5.h: ... here.
(kernel_u_size): Add prototype.  Improve a few comments and add
protection against multiple inclusion.