Clean up after java/openjdk6 and java/openjdk6-jre removal

java/openjdk6 support was removed from Mk/bsd.java.mk (r512662) and
java/openjdk6 and java/openjdk6-jre were removed from the ports tree
(r512663).  Now this patch completely removes remaining stuff from the
ports tree.

PR:			241953 (exp-run)
Reviewed by:		glewis
Approved by:		portmgr (antoine)
Differential Revision:	https://reviews.freebsd.org/D22342

java/jta/Makefile

@@ -12,7 +12,6 @@ COMMENT=	Java Transaction API (JTA)
 
 USES=		zip
 USE_JAVA=	yes
-JAVA_VERSION=	1.6+
 
 NO_BUILD=	yes
 NO_CDROM=	See the license