JDK 9 RFR of 8176846: (fc) Increase timeouts of and instrument some tests using FileChannel#write

[Brian Burkhalter]

Please review this test-only change.

Issue:	https://bugs.openjdk.java.net/browse/JDK-8176846
Patch:	http://cr.openjdk.java.net/~bpb/8176846/webrev.00/

Set the timeouts of the four tests to 300 sec (5 min.) and print to stdout the time taken to perform some large FileChannel#writes.

Thanks,

Brian