fix some warnings (#660)

Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

examples/component/composition.cpp

@@ -11,7 +11,7 @@ using namespace ftxui;
 
 // An example of how to compose multiple components into one and maintain their
 // interactiveness.
-int main(int argc, const char* argv[]) {
+int main() {
   auto left_count = 0;
   auto right_count = 0;