mongo-client: Handle systems without MSG_NOSIGNAL.
mongo-client: Handle systems without MSG_NOSIGNAL.

On systems that do not support MSG_NOSIGNAL, define it to 0. The
downside is that on such systems, applications will have to ignore
SIGPIPE themselves.

But this is far easier than working the problem around, and
implementing thread-safe SIGPIPE ignoring on these systems.

algernon/libmongo-client,algernon/libmongo-client,algernon/libmongo-client