blackfin: add missing const in function prototypes

Originally committed as revision 18976 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/bfin/dsputil_bfin.c

@@ -34,9 +34,9 @@ void ff_bfin_fdct (DCTELEM *block) attribute_l1_text;
 void ff_bfin_vp3_idct (DCTELEM *block);
 void ff_bfin_vp3_idct_put (uint8_t *dest, int line_size, DCTELEM *block);
 void ff_bfin_vp3_idct_add (uint8_t *dest, int line_size, DCTELEM *block);
-void ff_bfin_add_pixels_clamped (DCTELEM *block, uint8_t *dest, int line_size) attribute_l1_text;
-void ff_bfin_put_pixels_clamped (DCTELEM *block, uint8_t *dest, int line_size) attribute_l1_text;
-void ff_bfin_diff_pixels (DCTELEM *block, uint8_t *s1, uint8_t *s2, int stride)  attribute_l1_text;
+void ff_bfin_add_pixels_clamped (const DCTELEM *block, uint8_t *dest, int line_size) attribute_l1_text;
+void ff_bfin_put_pixels_clamped (const DCTELEM *block, uint8_t *dest, int line_size) attribute_l1_text;
+void ff_bfin_diff_pixels (DCTELEM *block, const uint8_t *s1, const uint8_t *s2, int stride)  attribute_l1_text;
 void ff_bfin_get_pixels  (DCTELEM *restrict block, const uint8_t *pixels, int line_size) attribute_l1_text;
 int  ff_bfin_pix_norm1  (uint8_t * pix, int line_size) attribute_l1_text;
 int  ff_bfin_z_sad8x8   (uint8_t *blk1, uint8_t *blk2, int dsz, int line_size, int h) attribute_l1_text;