window: Track and report input and opaque regions

We just set the input region to the bounding box of the window frame
and set the opaque region to be the opaque rectangle inside the window
if the child widget is opaque.

tests/matrix-test.c

@@ -222,11 +222,9 @@ static int
 test(void)
 {
 	struct weston_matrix m;
-	struct weston_matrix n;
 	double det, errsup;
 
 	randomize_matrix(&m);
-	n = m;
 	det = determinant(&m);
 
 	errsup = test_inverse(&m);
@@ -237,7 +235,7 @@ test(void)
 		return TEST_NOT_INVERTIBLE_OK;
 
 	printf("test fail, det: %g, error sup: %g\n", det, errsup);
-/*	print_matrix(&n);*/
+
 	return TEST_FAIL;
 }