GitLab

Problem reported by Glenn Morris in
<http://lists.gnu.org/archive/html/emacs-devel/2014-05/msg00277.html>.
Plus, fix some security and filename quoting problems.
* rcs2log (logdir): Prefer mktemp if available.
(logdir, llogdir): Work even if TMPDIR begins with '-' or has spaces.
(output_authors, main awk script): Parse more-recent CVS output format.