Fix an uninitialized variable.

Surprisingly, the actual initial value of this variable is
 irrelevant, since we always insert 24 bits of data into and then
 read only those bits out.
However, fixing this still removes undefined behavior and removes
 extraneous register dependencies.

src/info.c

@@ -473,6 +473,7 @@ static int opus_picture_tag_parse_impl(OpusPictureTag *_pic,const char *_tag,
   for(i=0;i<_base64_sz;i++){
     opus_uint32 value;
     int         j;
+    value=0;
     for(j=0;j<4;j++){
       unsigned c;
       unsigned d;