* tta/data/options_data.txt (LATEX_TAGGED_PDF),
tta/perl/Texinfo/Convert/LaTeX.pm (_latex_header): add
LATEX_TAGGED_PDF customization variable for LaTeX tagged PDF.  Report
form Charles Staats, David Carlisle example.

* tta/perl/Makefile.tres, tta/perl/t/latex_tests.t
(latex_tagged_pdf_default, latex_tagged_pdf_customized): add tests of
LaTeX tagged PDF.