Use correct oggz argument type in examples.

The examples using oggz must use oggz_package as the
second argument to read_package for the callback to be acceptable by
oggz_set_read_callback().  Adjust the method signature to use
oggz_package and extract the required ogg_package members from this
one to avoid compiler message like this:

fishsound-identify.c: In function ‘main’:
fishsound-identify.c:101:37: warning: passing argument 3 of ‘oggz_set_read_callback’ from incompatible pointer type [-Wincompatible-pointer-types]
  101 |   oggz_set_read_callback (oggz, -1, read_packet, NULL);
      |                                     ^~~~~~~~~~~
      |                                     |
      |                                     int (*)(OGGZ *, ogg_packet *, long int,  void *) {aka int (*)(void *, ogg_packet *, long int,  void *)}
In file included from /usr/include/oggz/oggz.h:576,
                 from fishsound-identify.c:39:
/usr/include/oggz/oggz_read.h:109:44: note: expected ‘OggzReadPacket’ {aka ‘int (*)(void *, oggz_packet *, long int,  void *)’} but argument is of type ‘int (*)(OGGZ *, ogg_packet *, long int,  void *)’ {aka ‘int (*)(void *, ogg_packet *, long int,  void *)’}
  109 |                             OggzReadPacket read_packet, void * user_data);
      |                             ~~~~~~~~~~~~~~~^~~~~~~~~~~

Fixes #13

src/examples/fishsound-decenc.c

@@ -129,9 +129,10 @@ decoded (FishSound * fsound, float ** pcm, long frames, void * user_data)
 }
 
 static int
-read_packet (OGGZ * oggz, ogg_packet * op, long serialno, void * user_data)
+read_packet (OGGZ * oggz, oggz_packet * ozp, long serialno, void * user_data)
 {
   FS_DecEnc * ed = (FS_DecEnc *) user_data;
+  ogg_packet *op = &ozp->op;
   
   fish_sound_prepare_truncation (ed->decoder, op->granulepos, op->e_o_s);
   fish_sound_decode (ed->decoder, op->packet, op->bytes);

src/examples/fishsound-decode.c

@@ -82,9 +82,10 @@ decoded_float (FishSound * fsound, float ** pcm, long frames, void * user_data)
 }
 
 static int
-read_packet (OGGZ * oggz, ogg_packet * op, long serialno, void * user_data)
+read_packet (OGGZ * oggz, oggz_packet * ozp, long serialno, void * user_data)
 {
   FishSound * fsound = (FishSound *)user_data;
+  ogg_packet *op = &ozp->op;
 
   /* If we have not yet selected an audio track to decode, then try
    * to identify this one. If it is a known audio codec, then remember its

src/examples/fishsound-identify.c

@@ -60,9 +60,9 @@ dump_identity (unsigned char * buf, long bytes)
 }
 
 static int
-read_packet (OGGZ * oggz, ogg_packet * op, long serialno, void * user_data)
+read_packet (OGGZ * oggz, oggz_packet * ozp, long serialno, void * user_data)
 {
-
+  ogg_packet *op = &ozp->op;
   if (op->bytes < 8) {
     printf ("too short\n");
   } else {

src/examples/fishsound-info.c

@@ -76,8 +76,9 @@ decoded (FishSound * fsound, float ** pcm, long frames, void * user_data)
 }
 
 static int
-read_packet (OGGZ * oggz, ogg_packet * op, long serialno, void * user_data)
+read_packet (OGGZ * oggz, oggz_packet * ozp, long serialno, void * user_data)
 {
+  ogg_packet *op = &ozp->op;
   FishSound * fsound = (FishSound *)user_data;
 
   if (op->e_o_s) {