Generate the version number used in the Autotools builds
via a script from the top-level CMakeLists.txt and git
information instead of manual editing.
This script mimics what the avrdude top-level CMakeLists.txt
does for composing AVRDUDE_FULL_VERSION.
Consequently, maintainers do not need to edit the version numbers
in the "src/configure.ac" file's "AC_INIT(...)" line any more.
However, unlike the cmake based builds, this does not print the
commit hash in the "avrdude --help" message or in the "avrdude.conf"
file's "avrdude_conf_version = " line. That will come later.
These are the six build types supported and what avrdude
versions cmake and the autoconf builds actually produce:
cmake autoconf
git clone release 7.2 7.2
git clone non-release 7.2-DATE+HASH 7.2-DATE
git archive release 7.2 7.2
git archive non-release 7.2 7.2
dist tarball release N/A 7.2
dist tarball non-release N/A 7.2-DATE
