3rdparty: bullet3: fix warning
3rdparty: bullet3: fix warning

mikymod/crown,mikymod/crown,galek/crown,mikymod/crown,taylor001/crown,galek/crown,mikymod/crown,taylor001/crown,taylor001/crown,dbartolini/crown,dbartolini/crown,dbartolini/crown,dbartolini/crown,taylor001/crown,galek/crown,galek/crown