If we call _clutter_stage_do_update() on a ClutterStage that isn't
mapped/visible, no GL command will be queued, and the Mesa/DRI2
implementation of SwapBuffers will do nothing. This causes
GLX_INTEL_swap_event to not be emitted by the X server because no swapping
has been requested through DRI2 and it eventually leads to a deadlock
situation in ClutterStageCogl because we're waiting for an event before we
start the next draw cycle.
This patch removes the non mapped stages from the list of stages to process.
This is consistent with a previous patch for the ClutterMasterClockGdk [1].
[1] : 5733ad58e5https://bugzilla.gnome.org/show_bug.cgi?id=755014
Nobody has been compiling Clutter with profiling enabled in a long time.
UProf itself hasn't been updated in 5 years, and it still depends on
deprecated components like dbus-glib, with no port to GDBus in sight.
The profiling code was moderately useful in the past, but these days
it's probably better to profile Cogl than Clutter itself; timing
information can be extracted by the timestamp on each diagnostic message
that is now available by default in the CLUTTER_NOTE macro, and we can
add ad hoc counters where needed.
