config: use eina_streq to optimize comparisons in _elm_config_color_overlay functions
config: use eina_streq to optimize comparisons in _elm_config_color_overlay functions

rvandegrift/elementary,tasn/elementary,rvandegrift/elementary,rvandegrift/elementary,tasn/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,tasn/elementary,FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary