improve raw pixels buffer tests
improve raw pixels buffer tests

EyalAr/lwip,EyalAr/lwip,fireball-x/lwip,weareu/lwip,mottx/lwip,EyalAr/lwip,fireball-x/lwip,fireball-x/lwip,domosapien/lwip,mottx/lwip,antoinepairet/lwip,weareu/lwip,weareu/lwip,mottx/lwip,mottx/lwip,antoinepairet/lwip,cocos-creator/lwip,cocos-creator/lwip,domosapien/lwip,antoinepairet/lwip,fireball-x/lwip,EyalAr/lwip,weareu/lwip,cocos-creator/lwip,domosapien/lwip,antoinepairet/lwip,cocos-creator/lwip,domosapien/lwip