i965/vec4: Silence unused parameter warnings in vec4 compiler tests

i965/vec4: Silence unused parameter warnings in vec4 compiler tests

src/intel/compiler/test_vec4_copy_propagation.cpp: In member function ‘virtual brw::dst_reg* copy_propagation_vec4_visitor::make_reg_for_system_value(int)’:
src/intel/compiler/test_vec4_copy_propagation.cpp:57:51: warning: unused parameter ‘location’ [-Wunused-parameter]
    virtual dst_reg *make_reg_for_system_value(int location)
                                                   ^~~~~~~~
src/intel/compiler/test_vec4_copy_propagation.cpp: In member function ‘virtual void copy_propagation_vec4_visitor::emit_urb_write_header(int)’:
src/intel/compiler/test_vec4_copy_propagation.cpp:77:43: warning: unused parameter ‘mrf’ [-Wunused-parameter]
    virtual void emit_urb_write_header(int mrf)
                                           ^~~
src/intel/compiler/test_vec4_copy_propagation.cpp: In member function ‘virtual brw::vec4_instruction* copy_propagation_vec4_visitor::emit_urb_write_opcode(bool)’:
src/intel/compiler/test_vec4_copy_propagation.cpp:82:57: warning: unused parameter ‘complete’ [-Wunused-parameter]
    virtual vec4_instruction *emit_urb_write_opcode(bool complete)
                                                         ^~~~~~~~
src/intel/compiler/test_vec4_register_coalesce.cpp: In member function ‘virtual brw::dst_reg* register_coalesce_vec4_visitor::make_reg_for_system_value(int)’:
src/intel/compiler/test_vec4_register_coalesce.cpp:60:51: warning: unused parameter ‘location’ [-Wunused-parameter]
    virtual dst_reg *make_reg_for_system_value(int location)
                                                   ^~~~~~~~
src/intel/compiler/test_vec4_register_coalesce.cpp: In member function ‘virtual void register_coalesce_vec4_visitor::emit_urb_write_header(int)’:
src/intel/compiler/test_vec4_register_coalesce.cpp:80:43: warning: unused parameter ‘mrf’ [-Wunused-parameter]
    virtual void emit_urb_write_header(int mrf)
                                           ^~~
src/intel/compiler/test_vec4_register_coalesce.cpp: In member function ‘virtual brw::vec4_instruction* register_coalesce_vec4_visitor::emit_urb_write_opcode(bool)’:
src/intel/compiler/test_vec4_register_coalesce.cpp:85:57: warning: unused parameter ‘complete’ [-Wunused-parameter]
    virtual vec4_instruction *emit_urb_write_opcode(bool complete)
                                                         ^~~~~~~~
src/intel/compiler/test_vec4_cmod_propagation.cpp: In member function ‘virtual brw::dst_reg* cmod_propagation_vec4_visitor::make_reg_for_system_value(int)’:
src/intel/compiler/test_vec4_cmod_propagation.cpp:60:51: warning: unused parameter ‘location’ [-Wunused-parameter]
    virtual dst_reg *make_reg_for_system_value(int location)
                                                   ^~~~~~~~
src/intel/compiler/test_vec4_cmod_propagation.cpp: In member function ‘virtual void cmod_propagation_vec4_visitor::emit_urb_write_header(int)’:
src/intel/compiler/test_vec4_cmod_propagation.cpp:85:43: warning: unused parameter ‘mrf’ [-Wunused-parameter]
    virtual void emit_urb_write_header(int mrf)
                                           ^~~
src/intel/compiler/test_vec4_cmod_propagation.cpp: In member function ‘virtual brw::vec4_instruction* cmod_propagation_vec4_visitor::emit_urb_write_opcode(bool)’:
src/intel/compiler/test_vec4_cmod_propagation.cpp:90:57: warning: unused parameter ‘complete’ [-Wunused-parameter]
    virtual vec4_instruction *emit_urb_write_opcode(bool complete)
                                                         ^~~~~~~~

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>