gallivm: (trivial) fix using one lod instead of per-quad lod for texel fetch
gallivm: (trivial) fix using one lod instead of per-quad lod for texel fetch

The logic for choosing number of lods was bogus.
(The code should ultimately handle the case of only one lod even with multiple
quads but currently can't.)

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