Fix bugs in XSP - Trying to identify why XSP freezes with Apache Bench

The use of lock to protect List<T> seems inconsistent in two parts of the FastCGI server.  I was able to reproduce failed enumerations due to unsynchronized access to the lists using Apache Bench.

Based on the bug open regarding send() not always sending the entire buffer size, even when the socket is in blocking mode, we need to actually check the return value of send functions that return int.  If send() never sends partial on blocking sockets, there should be no effect.