This commit uses the Register File Interest feature on z/OS
to enable users to monitor file system events.
The poll call is used to check for file descriptors as well
as a message queue that z/OS will report file system events
on. The last item on the list used by poll will contain the
message queue id instead of a file descriptor.
Limitation:
Writes to a directory (that is, file creation and deletion)
do not generate a change message for a registered directory.
PR-URL: https://github.com/libuv/libuv/pull/1311
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>