7020517: (fs) FileStore.equals returns true if both volumes have the same serial number

[Alan Bateman]

One of our tests, test/java/nio/file/Basic.java, fails on Windows when 
there are multiple drives mapped to the same remote file system. The 
problem is that the equals/hashCode methods are based on the volume 
serial number, which probably wasn't a good choice. To fix this I've 
changed the methods to use the volume mount point. The webrev with the 
changes is here:
  http://cr.openjdk.java.net/~alanb/7020517/webrev/

Thanks,
Alan