glsl: add lowering for double divide to rcp/mul
glsl: add lowering for double divide to rcp/mul

It looks like no hw does div anyways, so we should just
lower at the GLSL level.

Reviewed-by: Ilia Mirkin <bcbbb7aa705ec3a5fc5824c01a845186c3d62fca@alum.mit.edu>
Signed-off-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@redhat.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler