textproc/apache-solr upgrade to 7.4.0.
For more detail see here:
http://lucene.apache.org/solr/7_4_0/changes/Changes.html

Reviewed by: Ivo de Klerk <ivo@ixp.nl>
Approved by: tz (mentor)
Differential Revision: https://reviews.freebsd.org/D17371