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