RFR: 8129988: JSSE should create a single instance of the cacerts KeyStore

[Sean Mullan]

Please review this fix to modify the TrustManagerFactory implementation 
to create a single instance of the cacerts or jssecacerts KeyStore. This 
significantly improves performance in a multithreaded environment.

The code has been refactored a bit to move common code into a few 
private methods.

webrev: http://cr.openjdk.java.net/~mullan/webrevs/8129988/webrev.00/

Thanks,
Sean