[8u40] Review request 8064667: Provide support to help identify use of endorsed standards and extension mechanism

[Mandy Chung]

This requests both code review and 8u40 approval for:
    https://bugs.openjdk.java.net/browse/JDK-8064667

Webrev:
http://cr.openjdk.java.net/~mchung/jdk8u/webrevs/8064667/webrev.00/

JEP 220 [1] proposes to remove the endorsed standards override mechanism 
and extension mechanism. This patch adds a VM flag in 8u40 to help 
identify any existing uses of these mechanisms so that users can turn on 
the VM flag to help identify if they depend on the endorsed standards 
override mechanism and extension mechanism and can plan to prepare for 
the migration to a newer JDK release early on. When 
-XX:+CheckEndorsedAndExtDirs is set, the VM will exit if the system 
property -Djava.endorsed.dirs or -Djava.ext.dirs is set, or if 
${java.home}/lib/endorsed or ${java.home}/lib/ext exists, or any system 
extension directory contains JAR files.

Thanks
Mandy
[1] http://openjdk.java.net/jeps/220