dxgi/tests: Fix uninitialized variable warnings.

Signed-off-by: Zhiyi Zhang <zzhang@codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/dxgi/tests/dxgi.c

@@ -2123,7 +2123,7 @@ static void test_get_containing_output(void)
                 {-49, -50}, {-50, -50}, {-51, -50},
                 {-49, -51}, {-50, -51}, {-51, -51},
             };
-            unsigned int x, y;
+            unsigned int x = 0, y = 0;
 
             switch (i)
             {