In some cases the license-identification header was missing,
so I added that as well. Replaced the remaining headers that
specifically identified "Versions 3.13.7 and higher".
Makefiles and the build system were deliberately excluded.
Added -q (quiet) flag, renamed INSTALL_QUIETLY build variable.
Moved GENVERSION variables into normal locations.
Changed from :: rule to : rule with FORCE dependency.
Removed use of --git-dir, only works when CWD is TOP.
Simplified some parts, more perlish.
Added VCS used to generated output file.
Expanded on the -v (verbose) output.
Andrew Johnson