8206448: (fs) Extended attributes assumed to be enabled on ext3 (lnx)

[Brian Burkhalter]

https://bugs.openjdk.java.net/browse/JDK-8206448
http://cr.openjdk.java.net/~bpb/8206448/webrev.00/

Modified

1) not to assume that extended attributes are enabled by default on ext3, and
2) to assume that they are enabled by default on ext4 if and only if the kernel version is greater than or equal to 2.6.39.

Thanks,

Brian