security/sudo: Fix build with openssl from ports

Since SSL support is being changed and sudo can be built without it, add
a new SSL option, on by default.

When option is enabled, use --enable-openssl=${OPENSSLBASE} to make sure
it consumes desired OpenSSL implementation.  Also add pkgconfig
dependency because configure script rely on it to detect openssl
details.

PR:		274753
Reported by:	tburns@hrsd.com
Sponsored by:	Rubicon Communications, LLC ("Netgate")