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")

(cherry picked from commit dbc4e4daf752173acb868fc595ae9fa42f972aef)