The cast must use uint32_t. [ruby-core:34481]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@30541 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/zlib/zlib.c

@@ -2169,7 +2169,7 @@ gzfile_check_footer(struct gzfile *gz)
     if (gz->crc != crc) {
 	rb_raise(cCRCError, "invalid compressed data -- crc error");
     }
-    if ((int32_t)gz->z.stream.total_out != length) {
+    if ((uint32_t)gz->z.stream.total_out != length) {
 	rb_raise(cLengthError, "invalid compressed data -- length error");
     }
 }