Always emit signal after ShaderEffectSource::scheduleUpdate().

Always emit signal after ShaderEffectSource::scheduleUpdate().

The scheduledUpdateCompleted signal was originally added so that
you can take some action after updating a ShaderEffectSource with
scheduleUpdate(). However, before this commit, the signal would
not be emitted if the ShaderEffectSource was already up-to-date.
Instead, the signal would be delayed until the next time the
ShaderEffectSource was redrawn. This commit ensures the signal is
emitted even if the ShaderEffectSource is already up-to-date.

Change-Id: Idd22cdea1f7c14ed7a45081c98b8cfbef896dccd
Reviewed-by: Kim Gronholm <kim.1.gronholm@nokia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>