don't call redraw_all() from resize_event()

This messes up the redraw logic on macOS and is unnecessary, as the
redraw will happen anyways.

Author: wjakob

src/screen.cpp

@@ -862,8 +862,6 @@ bool Screen::keyboard_character_event(unsigned int codepoint) {
 bool Screen::resize_event(const Vector2i& size) {
     if (m_resize_callback)
         m_resize_callback(size);
-    m_redraw = true;
-    draw_all();
     return true;
 }