ranger: Fix `-Werror' build error with `ranger_cache::push_poor_value'

ranger: Fix `-Werror' build error with `ranger_cache::push_poor_value'

Remove a commit 86534c07a390 ("Disable poor value processing in ranger
cache.") regression that caused GCC not to build anymore if `-Werror'
has been enabled:

.../gcc/gimple-range-cache.cc: In member function 'bool ranger_cache::push_poor_value(basic_block, tree)':
.../gcc/gimple-range-cache.cc:850:44: error: unused parameter 'bb' [-Werror=unused-parameter]
  850 | ranger_cache::push_poor_value (basic_block bb, tree name)
      |                                ~~~~~~~~~~~~^~
.../gcc/gimple-range-cache.cc:850:53: error: unused parameter 'name' [-Werror=unused-parameter]
  850 | ranger_cache::push_poor_value (basic_block bb, tree name)
      |                                                ~~~~~^~~~

To keep the change to the minimum mark the parameters reported unused.

	gcc/
	* gimple-range-cache.cc (ranger_cache::push_poor_value): Mark
	parameters unused.