set PACKAGE and VERSION from the defines in the given specfile
default to basename and currentdate if rpmspecfile is not found
if the VERSION-number from the spec-file is shorter than 3 digits
then additional numbers are taken from the current date using
entries from `date` as %y and %W%w since libtool version numbers
can be as max only be 3 digits. The year counts from 1900.
result: (on 1. April 2002, being monday of 13th week)
see also AC_SET_RELEASEINFO_VERSIONINFO for the use of a 3VERSION