ports/189208: Add a mention of WITH_OPENSSL_PORT to the pkg-descr of security/openssl

[Garrett Wollman]

<<On Sat, 3 May 2014 12:55:36 -0500, Scot Hetzel <swhetzel at gmail.com> said:

> bsd.openssl.mk has the falling checks:

> if WITH_OPENSSL_BASE is set, then use the base system's OpenSSL.
> if WITH_OPENSSL_BASE or WITH_OPENSSL_PORT are not set, check if
> ${LOCALBASE}/lib/libcrypto.so is installed, if it is then use the
> OpenSSL port, otherwise use the base system's OpenSSL.
> if WITH_OPENSSL_PORT is set, then use the OpenSSL port

> So, if you install the OpenSSL port first, then ports that require
> OpenSSL should be built against the OpenSSL Port.

Doesn't work for package builds: the OpenSSL package will not be
installed prior to building the port unless the port depends on it.
On the other hand, it's probably necessary for non-poudriere builds,
because if your build environment *does* have the OpenSSL port
installed, chances are high that anything you build will end up
linking against it unless it's installed with a nonstandard PREFIX.

-GAWollman