Fix compile failure on OSX 10.9.4

``make`` failed with messages:

~~~text
src/gource_settings.cpp:1634:20: error: no member named 'cin' in namespace 'std'
        while(std::cin.peek() == EOF && !std::cin.fail()) SDL_Delay(100);
              ~~~~~^
src/gource_settings.cpp:1634:47: error: no member named 'cin' in namespace 'std'
        while(std::cin.peek() == EOF && !std::cin.fail()) SDL_Delay(100);
                                         ~~~~~^
src/gource_settings.cpp:1637:14: error: no member named 'cin' in namespace 'std'
        std::cin.clear();
        ~~~~~^
1 warning and 3 errors generated.
make: *** [src/mal4s-gource_settings.o] Error 1
~~~