build: rawvideo decoder depends on bswapdsp

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -2143,7 +2143,7 @@ qdm2_decoder_select="mdct rdft mpegaudiodsp"
 ra_144_encoder_select="audio_frame_queue lpc audiodsp"
 ra_144_decoder_select="audiodsp"
 ralf_decoder_select="golomb"
-rawvideo_decoder_select="dsputil"
+rawvideo_decoder_select="dsputil bswapdsp"
 rtjpeg_decoder_select="dsputil"
 rv10_decoder_select="error_resilience h263_decoder h263dsp mpeg_er"
 rv10_encoder_select="h263_encoder"