RFR: 8238959,: Add missing classpath exception to FileAcess and ConstantLookup

[Erik Gahlin]

Hi,

Could I have a review of a fix that adds missing class path exception to 
two files.

Webrev:
http://cr.openjdk.java.net/~egahlin/8238959/

Bug:
https://bugs.openjdk.java.net/browse/JDK-8238959

Testing:
test/jdk/jdk/jfr/*

Thanks
Erik