meta_wayland_seat_repick() can be called in various cases while mutter
has a GRAB_OP ongoing which means we could be sending wrong pointer
enter/leave events.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
This ensures that we send the proper leave and enter events to wayland
clients.
Particularly, this solves a bug in SSD xwayland windows where clicking
and dragging on the title bar to move the window only works on the odd
turn (unless the pointer moves away from the title bar between
tries). This happens because xwayland gets a button press but doesn't
see the release so when it gets the next button press it discards it
because its pointer button tracking logic says that the button is
already pressed. Sending the proper wayland pointer leave event fixes
it since wayland clients must forget about button state at that point.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
Commit e70a0109 simplified the dispatching of events by passing the event's
owernership to ClutterStage, but it may be so that any.stage is NULL at
some point on Windows, which will either cause _clutter_stage_queue_event()
to crash or issue a critical warning. Avoid this problem by checking
whether event->any.stage is not NULL before trying to call
_clutter_stage_queue_event().
https://bugzilla.gnome.org/show_bug.cgi?id=726765
...so that its entries will reflect the entries that are checked by the
autotools builds on config.h.in. Also take into consideration for MinGW
builds and for newer Visual Studio versions, such as the availability for
inttypes.h. Update the layout of the file cosmetic-wise as well.
Clutter, like GTK+ and GLib, has recently switched to a visibility-based
method of exporting symbols, so update the Visual Studio build files to
do likewise, by using __declspec (dllexport). This eliminats the need to
use a .def file to export the symbols. The pre-configured
config.h.win32.in is also updated accordingly for this purpose. The
clutter.symbols file can be dropped if it is not being used otherwise.
At one point, it was supported to run mutter without a compositor,
but we don't allow that any longer. A lot of code already assumes
display->compositor exists and doesn't check for a NULL pointer,
so just kill the rest of the checks.
