[TEST-BUG] JDK 9 RFR of 8173910: (fs) java/nio/file/FileSystem/Basic.java should conditionally check FileStores

[Brian Burkhalter]

Please review at your convenience.

Issue:	https://bugs.openjdk.java.net/browse/JDK-8173910
Patch:	http://cr.openjdk.java.net/~bpb/8173910/webrev.00/

Creation of a FileStore on Unix systems will hang if the stat(2) system call hangs which is the case for stale NFS mounts. The test is changed to spawn a ‘df’ command in a separate process and wait 90 seconds for that process to complete. If the process has not completed or its exit value is non-zero, the iteration over FileStores is omitted from the test. This should not affect most test runs and should suppress spurious failures due to stale NFS mounts.

Thanks,

Brian