Fixes the following warnings:
libavformat/chromaprint.c:117:42: warning: passing argument 2 of ‘chromaprint_feed’ from incompatible pointer type
libavformat/chromaprint.c:132:52: warning: passing argument 2 of ‘chromaprint_get_raw_fingerprint’ from incompatible pointer type
libavformat/chromaprint.c:143:71: warning: passing argument 4 of ‘chromaprint_encode_fingerprint’ from incompatible pointer type