* These generated the Makefile variables: clixon_DBSPECDIR, clixon_SYSCONFDIR, clixon_LOCALSTATEDIR, clixon_LIBDIR, clixon_DATADIR which have been replaced by generic autoconf variables instead.
* Backend startup modes prior to 3.3.3. As enabled with `configure --with-startup-compat`. Configure option CLICON_USE_STARTUP_CONFIG is also obsoleted.
* Configuration files (non-XML) prior to 3.3.3. As enabled with `configure --with-config-compat`. The template clicon.conf.cpp files are also removed.
* Clixon XML C-lib prior to 3.4.0. As enabled with `configure --with-xml-compat`
Add dist target to create project tarball. It uses a script called
version, that was obtained from vpp source code to produce a version
string using `git describe` that is incremental based on last annotated
tag available.