glsl: Silence unused parameter warning in propagate_invariance.cpp
glsl: Silence unused parameter warning in propagate_invariance.cpp

glsl/propagate_invariance.cpp: In member function ‘virtual ir_visitor_status {anonymous}::ir_invariance_propagation_visitor::visit_leave(ir_assignment*)’:
glsl/propagate_invariance.cpp:86:63: warning: unused parameter ‘ir’ [-Wunused-parameter]
 ir_invariance_propagation_visitor::visit_leave(ir_assignment *ir)
                                                               ^~

Signed-off-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler