[tlbuild] tl17 trial builds

[Karl Berry]

    ../../../libs/poppler/poppler-src/fofi/FoFiIdentifier.cc:73: error: expected ';' before 'override'

Does it work with the presumably-newer compiler on Debian 7?
I surmise it does. In which case that is the easiest way forward. Maybe
you can even compile dvisvgm and asy then :).

Anyway, that line is:
  int getByte(int pos) override;

So I surmise that that compiler version doesn't recognize "override",
and poppler makes no provision for older compilers.

I fear this is a stopper on most of ours systems. Looking at
poppler/poppler-src/configure.ac, evidently it also now unconditionally
wants to require -std=c++11:
  CXXFLAGS="$CXXFLAGS -std=c++11"

(I hadn't propagated that to TL's poppler/configure.ac, since I haven't
been investigating all configure changes in every release of every
package. Sigh.)

Anyway, not surprisingly, it fails for me also on the i386-linux I was
going to use. (CentOS 5, gcc version 4.1.2 20080704 (Red Hat 4.1.2-55);
it doesn't accept the above option.)

I guess we either have to revert to an older version of poppler, at
least for this year, or accept this brave new world of C++11 and use
newer systems or compilers. Or give up on TL. The world conspires to
make it ever-harder, never-easier, to make and distribute third-party
binaries, and it is all getting pretty discouraging. --karl