net/openldap24-server: fix build with LibreSSL

Modify the OpenSSL 1.1.1 preprocessor guards to also account for
LibreSSL missing certain functions, particularly
SSL_CTX_set_ciphersuites(3) and SSL_set_ciphersuites(3). While here,
un-IGNORE for ${SSL_DEFAULT:Mlibressl*}.

PORTREVISION intentionally not bumped as this is a build fix.

PR: 256433