do_release: Comment out release timestamp in configure.ac

immediately after release.
Rework increase of release number.  Remove usage of perl.
Ensure that only the number in the AC_INIT line is changed.

git-svn-id: https://svn.code.sf.net/p/smartmontools/code/trunk@5342 4ea69e1a-61f1-4043-bf83-b5c94c648137