build: Fix a compiler warning when using make dist
build: Fix a compiler warning when using make dist

Signed-off-by: Emmanuele Bassi <049ee2061f71220e5aaf33f5be422fc2a2b06a44@linux.intel.com>

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