[7u8] Request for approval for CR 7184815: [macosx] Need to read Kerberos config in files

[Weijun Wang]

Hi All

This is a request to backport a jdk8 fix into jdk7u8.
7184815: [macosx] Need to read Kerberos config in files

   http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7184815

After this change, the Java kerberos has a chance to read the system 
default /etc/krb5.conf file if no other config file is defined.

The fix is already included in jdk8 as:

   http://hg.openjdk.java.net/jdk8/tl/jdk/
   Reviewed-by: valeriep

The patch for jdk7u8 is identical to the one in jdk8.

Thanks
Weijun