[Midnightbsd-cvs] mports: bsd.mport.mk: add openal USE_OPENAL to simplify ports using this

[laffer1 at midnightbsd.org]

Log Message:
-----------
add openal USE_OPENAL to simplify ports using this

Modified Files:
--------------
    mports/Mk:
        bsd.mport.mk (r1.185 -> r1.186)
        (http://cvsweb.midnightbsd.org/mports/Mk/bsd.mport.mk?r1=1.185&r2=1.186)