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

This silences some of the -Wunused-function warnings when compiled with --disable-mmx, e.g
http://fate.ffmpeg.org/log.cgi?time=20150919094617&log=compile&slot=x86_64-archlinux-gcc-disable-mmx.
Header guards are too brittle and ugly for this case.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/x86/rnd_template.c

@@ -30,7 +30,7 @@
 #include "inline_asm.h"
 
 // put_pixels
-STATIC void DEF(put, pixels8_xy2)(uint8_t *block, const uint8_t *pixels,
+av_unused STATIC void DEF(put, pixels8_xy2)(uint8_t *block, const uint8_t *pixels,
                                   ptrdiff_t line_size, int h)
 {
     MOVQ_ZERO(mm7);
@@ -99,7 +99,7 @@ STATIC void DEF(put, pixels8_xy2)(uint8_t *block, const uint8_t *pixels,
 
 // avg_pixels
 // this routine is 'slightly' suboptimal but mostly unused
-STATIC void DEF(avg, pixels8_xy2)(uint8_t *block, const uint8_t *pixels,
+av_unused STATIC void DEF(avg, pixels8_xy2)(uint8_t *block, const uint8_t *pixels,
                                   ptrdiff_t line_size, int h)
 {
     MOVQ_ZERO(mm7);