[Midnightbsd-cvs] src: _null.h: fix null define for GCC

[laffer1 at midnightbsd.org]

Log Message:
-----------
fix null define for GCC

Modified Files:
--------------
    src/sys/sys:
        _null.h (r1.2 -> r1.3)
        (http://cvsweb.midnightbsd.org/src/sys/sys/_null.h?r1=1.2&r2=1.3)