r14920: allow a notify backend to separately specify if it has handled the

r14920: allow a notify backend to separately specify if it has handled the
given mask for the current directory and sub-directories. This allows
us to setup the less efficient internal handling for subdirectories,
while using the kernel inotify service for the current directory if
available. It also allows inotify to handle only some of the filter
bits, leaving the other filter bits for the user space handler.
(This used to be commit 7c3d989fa44c7f57853a825337159f476d7dff80)