openssl.3 dependency in bsd.openssl.mk can be satisfied by buggy base system openssl

[Bill Fenner]

>All ports using openssl will require openssl from ports,
>if your opensll in CURRENT/STABLE/RELEASE base system
>is not patched.
>
>Security: version in base must be 0.9.7d or have fixes
>http://www.freebsd.org/cgi/cvsweb.cgi/src/crypto/openssl/crypto/opensslv.h

So, I have a buggy version in base.  All ports that need openssl
get dependencies on openssl-0.9.7d, but that port isn't actually
installed.  The problem is:

...
OPENSSL_SHLIBVER?=      3
...
LIB_DEPENDS+=           crypto.${OPENSSL_SHLIBVER}:${PORTSDIR}/${OPENSSL_PORT}

fenestro% ls /usr/lib/libcrypto.so.*
/usr/lib/libcrypto.so.1 /usr/lib/libcrypto.so.2 /usr/lib/libcrypto.so.3

This /usr/lib/libcrypto.so.3 is version 0.9.7c from the FreeBSD 4.9
base system, but it satisfies the port LIB_DEPENDS=crypto.3 .

I realize I can install the openssl port to fix my system, but the
mechanism for deciding which SSL to use in the ports system is
broken.

  Bill