Fix redirected shoutcast ticket 12729

First commit fix a delete crash when testing ticket 12729, caused by buffer pointer not set to NULL after delete.

Second commit fix ticket 12729 by tell libcurl ignore content-length of shoutcast file.:
When the shoutcast file was 302 redirected, libcurl may return the content-length of the 302 page's body, it cause next read return 0.