anv/compiler: Get rid of legacy shader key setup
anv/compiler: Get rid of legacy shader key setup

Most of the shader key setup we did was for pre-Sandybridge and the stuff
for SNB+ wasn't in the key setup.  That stuff still isn't there but at
least we've left ourselves notes for now.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler