[Midnightbsd-cvs] mports: commands.mk: Use system xz if it exists

[laffer1 at midnightbsd.org]

Log Message:
-----------
Use system xz if it exists

Modified Files:
--------------
    mports/Mk/components:
        commands.mk (r1.4 -> r1.5)
        (http://cvsweb.midnightbsd.org/mports/Mk/components/commands.mk?r1=1.4&r2=1.5)