avcodec/x86/mpegvideoenc: silence -Wunused-function on --disable-mmx

This silences -Wunused-function when compiled with --disable-mmx, e.g
http://fate.ffmpeg.org/log.cgi?time=20150919094617&log=compile&slot=x86_64-archlinux-gcc-disable-mmx.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/x86/mpegvideoenc.c

@@ -86,6 +86,7 @@ DECLARE_ALIGNED(16, static uint16_t, inv_zigzag_direct16)[64];
 #endif /* HAVE_6REGS */
 
 #if HAVE_INLINE_ASM
+#if HAVE_MMX_INLINE
 static void  denoise_dct_mmx(MpegEncContext *s, int16_t *block){
     const int intra= s->mb_intra;
     int *sum= s->dct_error_sum[intra];
@@ -139,7 +140,9 @@ static void  denoise_dct_mmx(MpegEncContext *s, int16_t *block){
         : "r"(block+64)
     );
 }
+#endif /* HAVE_MMX_INLINE */
 
+#if HAVE_SSE2_INLINE
 static void  denoise_dct_sse2(MpegEncContext *s, int16_t *block){
     const int intra= s->mb_intra;
     int *sum= s->dct_error_sum[intra];
@@ -195,6 +198,7 @@ static void  denoise_dct_sse2(MpegEncContext *s, int16_t *block){
                             "%xmm4", "%xmm5", "%xmm6", "%xmm7")
     );
 }
+#endif /* HAVE_SSE2_INLINE */
 #endif /* HAVE_INLINE_ASM */
 
 av_cold void ff_dct_encode_init_x86(MpegEncContext *s)