Fixed compilation issue with gcc 4.6
Fixed compilation issue with gcc 4.6

zhenyw/beignet,zhenyw/beignet,ignatenkobrain/beignet,zhenyw/beignet,zhenyw/beignet,wdv4758h/beignet,ignatenkobrain/beignet,zhenyw/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet,ignatenkobrain/beignet,wdv4758h/beignet,freedesktop-unofficial-mirror/beignet,freedesktop-unofficial-mirror/beignet,ignatenkobrain/beignet,wdv4758h/beignet,ignatenkobrain/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet