Although "macOS" is the correct name for Apple's current desktop OS,
we've decided to go with "Mac OS" to cover all of Apple's Unix-like
desktop OS versions. The label "Mac OS" is more readable, clear in
context (i.e., unlikely to be confused with the Mac OSes that
proceeded Mac OS X), and as likely to match Apple's future OS names
as anything.
OS X's libssl is deprecated, and it doesn't work with SSL connections
that need SNI. We'll distribute out own libssl builds for OS X via a
package, but we need a native implementation that works well enough to
get that package.
The 'secure protocol symbol is just a shorthand for
`(ssl-secure-client-context)`, but it helps highlight
that the default 'auto isn't secure, and having a plain
symbol smooths the connection to native Win32 and OS X
implementations of SSL.
