minizip: Reapply Godot-specific changes for seek support

I have not assessed whether they are still all relevant.

thirdparty/minizip/unzip.h

@@ -202,6 +202,10 @@ extern int ZEXPORT unzClose OF((unzFile file));
     these files MUST be closed with unzipCloseCurrentFile before call unzipClose.
   return UNZ_OK if there is no problem. */
 
+/* GODOT start */
+extern void* unzGetOpaque(unzFile file);
+/* GODOT end */
+
 extern int ZEXPORT unzGetGlobalInfo OF((unzFile file,
                                         unz_global_info *pglobal_info));
 
@@ -390,6 +394,13 @@ extern int ZEXPORT unzReadCurrentFile OF((unzFile file,
     (UNZ_ERRNO for IO error, or zLib error for uncompress error)
 */
 
+/* GODOT start */
+extern int ZEXPORT unzSeekCurrentFile(unzFile file, int pos);
+/*
+  Seek to position in uncompressed data
+*/
+/* GODOT end */
+
 extern z_off_t ZEXPORT unztell OF((unzFile file));
 
 extern ZPOS64_T ZEXPORT unztell64 OF((unzFile file));