Sync-to-go: contrib/pdfmark..

Sync-to-go: contrib/pdfmark..

* pdfmark.tmac
- [b16be82] (Update copyright notices; pdfmark.tmac bug-fix,
  2010-12-23, Keith Marshall) fixes a thinko: in the other
  conditional branch .als is already used.
  (The name is "lost" after the operation anyway.)
- TODO [d64470f] (pdfmark.tmac (pdfmark, pdf:composed): Use `\!'
  instead of `\X'., 2013-01-28, Werner LEMBERG)
  Not integrated, as i don't understand what is going on.

* pdfroff.sh.in
- TODO Did not overtake (Deduce "--no-toc-relocation" from input
  stream).
- Took [94d17a8] (Avoid spurious user visible control messages on
  stderr., 2014-10-12, Keith Marshall), which injects a single
  ".pdfhref Z 0 0 0" "to ensure that at least one such is always
  present; ("this is required, to suppress any further
  intermediate output to stderr"[.]).
- TODO Did not take [b33e147] (Address potential temporary file
  security vulnerabilities., 2010-12-02, Keith Marshall).
  I think the right solution here will be the same that i have
  done for my mdocmx(1) preprocessor, i.e., "set -C" etc.
  TODO We will have a shell function library that gets installed
  TODO alongside S-roff, and allows safe creation of temporary
  TODO files -- use that, then.

In general it must be said that a multi-pass troff(1) would be
able to support much of the grohtml(1) desaster but also
pdfroff.sh in one go.  It should be up to the macros to do all
that!