fix [x11]: compiler warnings in floatbar

fix [x11]: compiler warnings in floatbar

client/X11/xf_floatbar.c:530:27: warning: use of logical '&&' with constant
      operand [-Wconstant-logical-operand]
        if (event->xmotion.state && Button1Mask && mode > XF_FLOATBAR_MODE_DRAGGING)
                                 ^  ~~~~~~~~~~~
client/X11/xf_floatbar.c:534:32: warning: use of logical '&&' with constant
      operand [-Wconstant-logical-operand]
        else if (event->xmotion.state && Button1Mask && mode == XF_FLOATBAR_MODE_DRAGGING)
                                      ^  ~~~~~~~~~~~
clang 8.0.0-svn344413-1~exp1+0~20181012203207.819~1.gbpc91f27