intel: Use GL_FRONT_AND_BACK for stencil clearing.
intel: Use GL_FRONT_AND_BACK for stencil clearing.

This comes from a radeon-rewrite fallback fix, but may also fix stencil
clear failure when the polygon winding mode is flipped.
(cherry picked from commit d866abeffc7e4a29736fa35fb8ac09c3a28a44d6)

mapbox/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,metora/MesaGLSLCompiler,zz85/glsl-optimizer,adobe/glsl2agal,mapbox/glsl-optimizer,KTXSoftware/glsl2agal,djreep81/glsl-optimizer,benaadams/glsl-optimizer,adobe/glsl2agal,zeux/glsl-optimizer,KTXSoftware/glsl2agal,adobe/glsl2agal,mapbox/glsl-optimizer,bkaradzic/glsl-optimizer,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,KTXSoftware/glsl2agal,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,tokyovigilante/glsl-optimizer,mcanthony/glsl-optimizer,wolf96/glsl-optimizer,bkaradzic/glsl-optimizer,jbarczak/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,jbarczak/glsl-optimizer,dellis1972/glsl-optimizer,dellis1972/glsl-optimizer,benaadams/glsl-optimizer,dellis1972/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,mcanthony/glsl-optimizer,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,tokyovigilante/glsl-optimizer,mcanthony/glsl-optimizer,mcanthony/glsl-optimizer,dellis1972/glsl-optimizer,metora/MesaGLSLCompiler,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,tokyovigilante/glsl-optimizer,metora/MesaGLSLCompiler,mapbox/glsl-optimizer,dellis1972/glsl-optimizer,djreep81/glsl-optimizer,adobe/glsl2agal,KTXSoftware/glsl2agal,zeux/glsl-optimizer,jbarczak/glsl-optimizer,djreep81/glsl-optimizer,adobe/glsl2agal,bkaradzic/glsl-optimizer,KTXSoftware/glsl2agal,mapbox/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,benaadams/glsl-optimizer,djreep81/glsl-optimizer,djreep81/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer