Package librpm7: Information

- Packaged the forgtotten new rpmvercmp.h (whose use is discouraged
  in favor of rpmEVRDTCompare() or rpmRangesOverlap()).

- lib: introduced rpmEVRDTCompare() (useful for APT).
- Changes in what is considered "newer" by rpm -U  pertaining to disttag
  comparison. (On the whole, to determine which package is "newer", first,
  the EVRs are compared, then the branch prefixes of the disttags if the
  disttags are present, and then the buildtimes.) The comparison of the disttags:
  + Before the comparison of disttags, an optional initial padding
    (which is terminated by :) is skipped. (This will be useful for
    generating >,<-deps compatible with disttag-unaware rpm & apt.)
  + If a disttag contains no + separator (old format), the branch prefix is
    assumed to be empty (and hence "older" than any other branch prefix).
  + If the branch prefix of a disttag is equal to %_priority_distbranch
    (and it is not empty), then it is "newer" than any other ones.
  + The branch prefixes of disttags are ordered by rpmvercmp() rather than
    lexicographically. (For example, the numeric parts of "p8" or "p10" are
    compared as numbers. However, the first letter in "p7" or "c8.1" is more
    significant.)
- Give a default value to %_priority_distbranch based on the disttag
  when this package is built (the prefix before +),
  i.e., the current repo branch by default.
  (Useful for getting the rpm tool with good behavior in branches (like p9)
  forked off Sisyphus after disttags were introduced.)

- Fix crash in syslog plugin (closes: #35722).
- Fix setting permissions for hardlinked files even if some
  of the files are skipped (closes: #32997).