JDK 9 RFR of 8150204: (fs) Enhance java/nio/file/Files/probeContentType/Basic.java debugging output

[Brian Burkhalter]

Please review at your convenience this sub-task of https://bugs.openjdk.java.net/browse/JDK-8146215:

Issue:	https://bugs.openjdk.java.net/browse/JDK-8150204
Patch:	http://cr.openjdk.java.net/~bpb/8150204/webrev.00/

Summary:

If the test is running on Unix and a content type (for the bogus “grape” and the real “html” types) is obtained which differs from that which would respectively have been expected, then check for the existence and readability of /etc/mime.types and $user.home/.mime.types and print information to the maximum extent available about each of these files: 1) contents, 2) readability, 3) existence.

Note that this does not help to run down whether relevant native-based file type detectors had been loaded on Linux {libgio, libmagic} or Solaris {libgio}. It would be helpful if it were possible for that sort of native initialization information to be available somehow to the test.

Thanks,

Brian