change include "nut.h" to <nut.h> to make gcc pick the correct nut.h for libnut de/muxer..

Originally committed as revision 6985 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/libnut.c

 #include "avformat.h"
 #include "riff.h"
-#include "nut.h"
+#include <nut.h>
 
 #define ID_STRING "nut/multimedia container"
 #define ID_LENGTH (strlen(ID_STRING) + 1)