textproc/re-flex: update to 1.6.4
Release notes: https://github.com/Genivia/RE-flex/releases/tag/v1.6.1 https://github.com/Genivia/RE-flex/releases/tag/v1.6.2 https://github.com/Genivia/RE-flex/releases/tag/v1.6.3 https://github.com/Genivia/RE-flex/releases/tag/v1.6.4