configure.ac: move gles checks after the flavour checks
configure.ac: move gles checks after the flavour checks

The flavour AS_CASE should define whether a flavour uses the gl or gles
COGL_DRIVER and so we shouldn't need to have an expanding list of
tests to gate when we check for a gles driver because if we move the
checks for gles after the flavour checks we can just look at
$COGL_DRIVER.

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