C++ APIs wrapping SS client
These are intended to provide an experimental protocol-independent c++
api even more abstracted than secure streams, along the lines of
"wget -Omyfile https://example.com/thing"
WIP
From eventfd man page:
Applications can use an eventfd file descriptor instead of a pipe (see
pipe(2)) in all cases where a pipe is used simply to signal events.
The kernel overhead of an eventfd file descriptor is much lower than
that of a pipe, and only one file descriptor is required
(versus the two required for a pipe).
