avcodec/avdct: Add avcodec_dct_get_class()

This should have been in the initial commit of AVDCT
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/avdct.c

@@ -70,6 +70,11 @@ static const AVClass avdct_class = {
     .version                 = LIBAVUTIL_VERSION_INT,
 };
 
+const AVClass *avcodec_dct_get_class(void)
+{
+    return &avdct_class;
+}
+
 AVDCT *avcodec_dct_alloc(void)
 {
     AVDCT *dsp = av_mallocz(sizeof(AVDCT));

libavcodec/avdct.h

@@ -73,4 +73,6 @@ typedef struct AVDCT {
 AVDCT *avcodec_dct_alloc(void);
 int avcodec_dct_init(AVDCT *);
 
+const AVClass *avcodec_dct_get_class(void);
+
 #endif /* AVCODEC_AVDCT_H */