premium config/build fixes and cleanups
Set SHARE_DIR
(cf #5639 3. bug)
Made freeradius checks conditional on the radius hook existence.
Find an usage or remove config.setup
Move m4_sinclude
calls to top-level (it is an illusion to believe they can be conditional)
Cleanup Makefile.in
Investigate if distcheck with and without autoreconf works (aka Marcin's test). If not either fix and document as not working.