checkasm: Provide enough alignment in the new motion test

This fixes the checkasm test in some setups on x86.

Signed-off-by: Martin Storsjö <martin@martin.st>

tests/checkasm/motion.c

@@ -48,8 +48,8 @@ static void test_motion(const char *name, me_cmp_func test_func)
     int i, x, y, d1, d2;
     uint8_t *ptr;
 
-    LOCAL_ALIGNED_8(uint8_t, img1, [WIDTH * HEIGHT]);
-    LOCAL_ALIGNED_8(uint8_t, img2, [WIDTH * HEIGHT]);
+    LOCAL_ALIGNED_16(uint8_t, img1, [WIDTH * HEIGHT]);
+    LOCAL_ALIGNED_16(uint8_t, img2, [WIDTH * HEIGHT]);
 
     declare_func_emms(AV_CPU_FLAG_MMX, int, struct MpegEncContext *c,
                       uint8_t *blk1 /* align width (8 or 16) */,