RFR: 8165712: Grant permission to read specific properties instead of all to the jdk.crypto.ucrypto module

[Sean Mullan]

Please review this fix to only grant the necessary PropertyPermissions 
to the jdk.crypto.ucrypto module.

In UcryptoProvider I also moved the System.getProperty("os.name") inside 
doPrivileged (just in case permission to read this property has not been 
granted to the caller) and did some minor refactoring.

http://cr.openjdk.java.net/~mullan/webrevs/8167512/webrev.00/

--Sean