sdl2: city_map_canvas not freed on client exit
Reply To cazfi
Should be fixed just so that it won't show up in valgrind reports any more
These fixes actually handle also such an issue that the city_map_canvas pointer was not initialized, and if it happened to be non-NULL it was assumed to contain a valid value to free() before reallocation. To fix that more serious aspect made also S2_6 version.
sdl2-client does not free city_map_canvas on exit. Should be fixed just so that it won't show up in valgrind reports any more (possibly causing people to investigate the situation over and over)