checkasm: swscale: Fix running the hscale test on 32 bit x86

This function doesn't call emms.

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

tests/checkasm/sw_scale.c

@@ -63,7 +63,7 @@ static void check_hscale(void)
 
     // The dst parameter here is either int16_t or int32_t but we use void* to
     // just cover both cases.
-    declare_func(void, void *c, void *dst, int dstW,
+    declare_func_emms(AV_CPU_FLAG_MMX, void, void *c, void *dst, int dstW,
                       const uint8_t *src, const int16_t *filter,
                       const int32_t *filterPos, int filterSize);