Assign bit gravity to window in Lucid and Motif ports too

* src/widget.c (EmacsFrameRealize): Assign bit_gravity, and use
the value of NorthWestGravity which matches the GTK3 behavior,
and the general intuition that window's contents should move
with its top-left corner.  The result is that the frame is not
blinking during resizing (bug#80369).

* src/xfns.c (x_window) [!USE_X_TOOLKIT]: Change bit_gravity from
StaticGravity to NorthWestGravity as well, to match the others.

src/widget.c

@@ -392,7 +392,9 @@ EmacsFrameRealize (Widget widget, XtValueMask *mask,
   attrs->event_mask = (STANDARD_EVENT_SET
 		       | PropertyChangeMask
 		       | SubstructureNotifyMask);
+  attrs->bit_gravity = NorthWestGravity;
   *mask |= CWEventMask;
+  *mask |= CWBitGravity;
   XtCreateWindow (widget, InputOutput, (Visual *) CopyFromParent, *mask,
 		  attrs);
   /* Some ConfigureNotify events does not end up in EmacsFrameResize so

src/xfns.c

@@ -4483,7 +4483,7 @@ x_window (struct frame *f)
 
   attributes.background_pixel = FRAME_BACKGROUND_PIXEL (f);
   attributes.border_pixel = f->output_data.x->border_pixel;
-  attributes.bit_gravity = StaticGravity;
+  attributes.bit_gravity = NorthWestGravity;
   attributes.backing_store = NotUseful;
   attributes.save_under = True;
   attributes.event_mask = STANDARD_EVENT_SET;