[FIX] Frame buffer clearing now works if flags are zero.
[FIX] Frame buffer clearing now works if flags are zero.

SuperStarPL/engine,maxwellalive/engine,3DGEOM/engine,sanyaade-teachings/engine,RainsSoft/engine,shinate/engine,MicroWorldwide/PlayCanvas,horryq/engine-1,MicroWorldwide/PlayCanvas,guycalledfrank/engine,RainsSoft/engine,maxwellalive/engine,SuperStarPL/engine,guycalledfrank/engine,sereepap2029/playcanvas,sereepap2029/playcanvas,maxwellalive/engine,playcanvas/engine,horryq/engine-1,shinate/engine,RainsSoft/engine,horryq/engine-1,3DGEOM/engine,H1Gdev/engine,shinate/engine,playcanvas/engine,nizihabi/engine,H1Gdev/engine,sereepap2029/playcanvas,aidinabedi/playcanvas-engine,sanyaade-teachings/engine,aidinabedi/playcanvas-engine,SuperStarPL/engine,sanyaade-teachings/engine,nizihabi/engine,nizihabi/engine,3DGEOM/engine