revert the removal of MwLLBeginDraw/EndDraw, turns out the newer system still doesn't please weston and likely other compositors

src/backend/call.c

@@ -8,8 +8,10 @@
 		MwLLCreate  = MwLLCreateImpl; \
 		MwLLDestroy = MwLLDestroyImpl; \
 \
-		MwLLPolygon = MwLLPolygonImpl; \
-		MwLLLine    = MwLLLineImpl; \
+		MwLLPolygon   = MwLLPolygonImpl; \
+		MwLLLine      = MwLLLineImpl; \
+		MwLLBeginDraw = MwLLBeginDrawImpl; \
+		MwLLEndDraw   = MwLLEndDrawImpl; \
 \
 		MwLLAllocColor	= MwLLAllocColorImpl; \
 		MwLLColorUpdate = MwLLColorUpdateImpl; \

src/backend/cocoa.m

@@ -1001,6 +1001,14 @@ static void MwLLDestroyImpl(MwLL handle) {
 	free(handle);
 }
 
+static void MwLLBeginDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
+static void MwLLEndDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
 static void MwLLPolygonImpl(MwLL handle, MwPoint* points, int points_count,
 			    MwLLColor color) {
 	MilskoCocoa* h = handle->cocoa.real;

src/backend/gdi.c

@@ -310,6 +310,14 @@ static void MwLLDestroyImpl(MwLL handle) {
 	free(handle);
 }
 
+static void MwLLBeginDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
+static void MwLLEndDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
 static void MwLLPolygonImpl(MwLL handle, MwPoint* points, int points_count, MwLLColor color) {
 	POINT* p   = malloc(sizeof(*p) * points_count);
 	HPEN   pen = CreatePen(PS_NULL, 0, RGB(0, 0, 0));

src/backend/wayland.c

@@ -1531,6 +1531,14 @@ refresh:
 	MwLLDispatch(handle, draw, NULL);
 }
 
+static void MwLLBeginDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
+static void MwLLEndDrawImpl(MwLL handle) {
+	update_buffer(&handle->wayland.framebuffer);
+}
+
 static void MwLLPolygonImpl(MwLL handle, MwPoint* points, int points_count, MwLLColor color) {
 	int i;
 	cairo_set_source_rgb(handle->wayland.cairo, color->common.red / 255.0, color->common.green / 255.0, color->common.blue / 255.0);

src/backend/x11.c

@@ -261,8 +261,15 @@ static void MwLLDestroyImpl(MwLL handle) {
 	free(handle);
 }
 
-static void
-MwLLPolygonImpl(MwLL handle, MwPoint* points, int points_count, MwLLColor color) {
+static void MwLLBeginDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
+static void MwLLEndDrawImpl(MwLL handle) {
+	(void)handle;
+}
+
+static void MwLLPolygonImpl(MwLL handle, MwPoint* points, int points_count, MwLLColor color) {
 	int	i;
 	XPoint* p = malloc(sizeof(*p) * points_count);