JDWinMain: Unite if-statement blocks for same condition

[ma8ma]

隣り合うif文が同じ条件であるとcppcheckに指摘されたためブロックをまとめます。

cppcheckのレポート

src/winmain.cpp:281:9: style: The if condition is the same as the previous if condition [duplicateCondition]
    if( m_cancel_state_event ) return Gtk::Window::on_window_state_event( event );
        ^
src/winmain.cpp:277:9: note: First condition
    if( m_cancel_state_event ) std::cout << "cancel\n";
        ^
src/winmain.cpp:281:9: note: Second condition
    if( m_cancel_state_event ) return Gtk::Window::on_window_state_event( event );
        ^
src/winmain.cpp:295:9: style: The if condition is the same as the previous if condition [duplicateCondition]
    if( m_cancel_state_event ) return Gtk::Window::on_configure_event( event );
        ^
src/winmain.cpp:291:9: note: First condition
    if( m_cancel_state_event ) std::cout << "cancel\n";
        ^
src/winmain.cpp:295:9: note: Second condition
    if( m_cancel_state_event ) return Gtk::Window::on_configure_event( event );
        ^