dri/radeon: test for FEATURE defines
dri/radeon: test for FEATURE defines

'struct dd_function_table' only conditionally contains
the function pointer NewFramebuffer and friends based on
FEATURE_EXT_framebuffer_* defines. (See src/mesa/main/dd.h)

Fixes the build when the features are disabled and the vfuncs
don't exist.

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