client API: fix missing property change events after property updates

When update_prop() successfully fetched a changed property value, it
set prop->changed to true to indicate the success.
mark_property_changed() also always set
prop->changed to true and additionally prop->need_new_value to true
This is the case since 6ac0ef78
If the observed property changes every frame and then due to timing
the next mark_property_changed() is called before
gen_property_change_event() and therefore directly after update_prop(),
prop->need_new_value was again true and indicated that a new value
has to be retrieved with update_prop(). As a result the event for the
last successful update_prop() was never triggered. This meant that
a property change event were never generated for frame-based properties
only for properties that were observed with MPV_FORMAT_NONE or when the
timing was different and gen_property_change_event() was called after
update_prop().

To fix this, mark_property_change() and update_prop() should not use the
same flag to indicate different things and therefore a new flag for
successfully update a property is introduced. But with the now decoupled property
changed and updated the need_new_value flag is redundant and removed completely.

Fixes #4195

0 files changed, 0 insertions, 0 deletions