[Midnightbsd-cvs] mports: bsd.mport.mk: Don't include xz dependancy when os version is

[laffer1 at midnightbsd.org]

Log Message:
-----------
Don't include xz dependancy when os version is greater than 4003 when we introduced it in the base.

Modified Files:
--------------
    mports/Mk:
        bsd.mport.mk (r1.176 -> r1.177)
        (http://cvsweb.midnightbsd.org/mports/Mk/bsd.mport.mk?r1=1.176&r2=1.177)