nir: Add opt_algebraic rules for xor with zero.
nir: Add opt_algebraic rules for xor with zero.

instructions in affected programs: 668 -> 664 (-0.60%)
helped: 4

Reviewed-by: Eduardo Lima Mitev <86e6f0c9eba14994f25948ad50c226b324e9fa92@igalia.com>
Reviewed-by: Jason Ekstrand <b186559eaedf698788888c8a2559b4efb4db10d6@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler