Revert "thdat02: don't try to free() a mapping"

This reverts commit eae5642.

PR #119 fixes this in a better way

thtk/thdat02.c

@@ -141,13 +141,7 @@ th02_read(
         ret = thtk_io_write(output, data, entry->zsize, error);
         free(data);
     } else {
-        /* FIXME: ouch, an unnecessary copy, due to thtk_io_open_memory taking ownership */
-        void *data2 = malloc(entry->zsize);
-        if (!data2)
-            return -1;
-        memcpy(data2, data, entry->zsize);
-
-        thtk_io_t* data_stream = thtk_io_open_memory(data2, entry->zsize, error);
+        thtk_io_t* data_stream = thtk_io_open_memory(data, entry->zsize, error);
         if (!data_stream)
             return -1;
         ret = thtk_unrle(data_stream, entry->zsize, output, error);