Fixed buffer overrun after changing chunk size.
Fixed buffer overrun after changing chunk size.

Thanks to Zengxian Ding.

arut/nginx-rtmp-module,arut/nginx-rtmp-module,DavadDi/nginx-rtmp-module,arut/nginx-rtmp-module,DavadDi/nginx-rtmp-module,DavadDi/nginx-rtmp-module,arut/nginx-rtmp-module