[texture] fix load-async and load-data-async properties.
[texture] fix load-async and load-data-async properties.

Removed the G_PARAM_CONSTRUCT from the property registration of
"load-async" and "load-data-async". It made it impossible to use only
load-data-async, as the async loading state would be unset when
load-async got set it's default FALSE value.

nobled/clutter,ebassi/clutter,djdeath/clutter,ebassi/clutter,Distrotech/clutter,jigpu/clutter,djdeath/clutter,GNOME/clutter,nobled/clutter,nobled/clutter,jigpu/clutter,collects/clutter,jigpu/clutter,spatulasnout/clutter,dlespiau/clutter,spatulasnout/clutter,djdeath/clutter-android,ebassi/clutter,heysion/clutter-clone,djdeath/clutter-multithreaded,collects/clutter,jigpu/clutter,Distrotech/clutter,djdeath/clutter,tardyp/clutter,collects/clutter,djdeath/clutter-android,kerrickstaley/clutter-vala,djdeath/clutter-android,kerrickstaley/clutter-vala,spatulasnout/clutter,kerrickstaley/clutter-vala,spatulasnout/clutter,ebassi/clutter,rkudiyarov/clutter_osx,djdeath/clutter-android,kerrickstaley/clutter-vala,collects/clutter,Distrotech/clutter,spatulasnout/clutter,GNOME/clutter,rkudiyarov/clutter_osx,rkudiyarov/clutter_osx,djdeath/clutter,tardyp/clutter,djdeath/clutter-android,djdeath/clutter-multithreaded,collects/clutter,dlespiau/clutter,djdeath/clutter,Distrotech/clutter,GNOME/clutter,heysion/clutter-clone,dlespiau/clutter,GNOME/clutter,djdeath/clutter,heysion/clutter-clone,rkudiyarov/clutter_osx,djdeath/clutter-multithreaded,tardyp/clutter,jigpu/clutter,jigpu/clutter,djdeath/clutter-multithreaded,heysion/clutter-clone,ebassi/clutter,Distrotech/clutter,heysion/clutter-clone,GNOME/clutter,Distrotech/clutter