glx: handle spurious GLX_BufferSwapComplete events gracefully
glx: handle spurious GLX_BufferSwapComplete events gracefully

Instead of simply aborting we now print out a warning, when a spurious
GLX_BufferSwapComplete event is handled since it seems that people are
coming across the problem (perhaps due to a buggy driver) and making
apps crash in this situation is a bit extreme.

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