RFR: JDK-8210924 Remove PACKAGE_PATH

[Magnus Ihse Bursie]

The variable PACKAGE_PATH crept into the build when the macosx port was 
integrated. It is not used, however, and should be removed. (This is a 
BSD construct, and the macosx port was based on the BSD port.)

If/when the BSD port ever gets integrated upstream, we'll know better 
then how to restore PACKAGE_PATH on the proper places.

Bug: https://bugs.openjdk.java.net/browse/JDK-8210924
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8210924-remove-PACKAGE_PATH/webrev.01

/Magnus