[2] Remove an unnecessary configure script from when this was built from
monolithic sources.
[3] Register conflicts for dri-devel in dri.
Submitted by: [1] krismail
[2] Respect CXXFLAGS a little more thoroughly.
PR: [1] ports/75473
Submitted by: [1] KIMURA Yasuhiro, yasu at utahime dot org, among many others
Based on: [1] patch by thierry