Remove one more forgotten instance of USE_HIGHPRECISION indirection.

Originally committed as revision 16597 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpc.h

@@ -32,10 +32,6 @@
 #include "avcodec.h"
 #include "bitstream.h"
 #include "dsputil.h"
-
-#if CONFIG_MPEGAUDIO_HP
-#define USE_HIGHPRECISION
-#endif
 #include "mpegaudio.h"
 
 #include "mpcdata.h"