svga: always link with C++
svga: always link with C++

Even when we don't have LLVM since there's other C++ code
in the resulting DRI driver object.

Note: This is a candidate for the stable branches.

Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

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