Move ff_dct_init_mmx declaration to dct.h

This was missed in 0aded948.
Signed-off-by: Mans Rullgard <mans@mansr.com>

libavcodec/dct.h

@@ -47,4 +47,6 @@ struct DCTContext {
 int  ff_dct_init(DCTContext *s, int nbits, enum DCTTransformType type);
 void ff_dct_end (DCTContext *s);
 
+void ff_dct_init_mmx(DCTContext *s);
+
 #endif

libavcodec/fft.h

@@ -99,7 +99,6 @@ int ff_fft_init(FFTContext *s, int nbits, int inverse);
 void ff_fft_init_altivec(FFTContext *s);
 void ff_fft_init_mmx(FFTContext *s);
 void ff_fft_init_arm(FFTContext *s);
-void ff_dct_init_mmx(DCTContext *s);
 
 void ff_fft_end(FFTContext *s);