cogl/configure.ac: make COGL_HAS_xyz defines public
cogl/configure.ac: make COGL_HAS_xyz defines public

Instead of using AC_DEFINE for the various COGL_HAS_PLATFORM defines
this now adds them to the COGL_DEFINES_SYMBOLS variable which gets
substituted into the public cogl-defines.h header.

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