build: fix standalone compilation of mpc7/mpc8 decoders

These decoders depend on the mpegaudio DSP code.

diff --git a/configure b/configure
index 22542af..180578d 100755 (executable)
--- a/configure
+++ b/configure
@@ -1324,6 +1324,8 @@ mp3adufloat_decoder_select="mpegaudiodsp"
 mp3float_decoder_select="mpegaudiodsp"
 mp3on4_decoder_select="mpegaudiodsp"
 mp3on4float_decoder_select="mpegaudiodsp"
+mpc7_decoder_select="mpegaudiodsp"
+mpc8_decoder_select="mpegaudiodsp"
 mpeg_vdpau_decoder_select="vdpau mpegvideo_decoder"
 mpeg_xvmc_decoder_deps="X11_extensions_XvMClib_h"
 mpeg_xvmc_decoder_select="mpegvideo_decoder"