RFR 6562449: LoginContext does not all allow overloading of login method in LoginModule

[Jamil Nimeh]

Hello all,

This webrev covers a fix to LoginContext so it no longer selects the 
wrong method when a LoginModule method (login, logout, commit, etc.) has 
been overloaded.

Bug: https://bugs.openjdk.java.net/browse/JDK-6562449
Webrev: http://cr.openjdk.java.net/~ascarpino/6562449/webrev.01

Thank you,
--Jamil