bsd.own.mk fix

[William Wisner <wisner_(_at_)_gryphon_(_dot_)_com>]

In share/mk/bsd.port.mk the definition of INSTALL_DATA references
undefined variables SHAREGRP, SHAREOWN and SHAREMODE.  Define
them, as well as SHAREDIR for completeness:

*** share/mk/bsd.own.mk.orig	Sat Apr 19 22:31:46 1997
--- share/mk/bsd.own.mk	Sat Apr 19 22:32:32 1997
***************
*** 42,47 ****
--- 42,52 ----
  LIBOWN?=	${BINOWN}
  LIBMODE?=	${NONBINMODE}
  
+ SHAREDIR?=	/usr/share
+ SHAREGRP?=	wheel
+ SHAREOWN?=	root
+ SHAREMODE?=	${NONBINMODE}
+ 
  DOCDIR?=        /usr/share/doc
  DOCGRP?=	bin
  DOCOWN?=	root