Xenial regression, unescaped percent pound, dollar sign in doxygen latex output

[Daniel Wang]

Description of problem:
there's a problem to build documentation for the apron package in Xenial. With doxygen 1.8.11, documentation for a certain operator% looks like this:

\subsubsection[{operator%(const texpr1+::builder &a, const texpr1+::builder &b)}]{\setlength{\rightskip}{0pt plus 5cm}texpr1+::builder operator% (
\begin{DoxyParamCaption}
\item[{const texpr1+::builder &}]{a, }
\item[{const texpr1+::builder &}]{b}
\end{DoxyParamCaption}

That works fine. However, with 1.8.11, this is produced:

\subsubsection[{\texorpdfstring{operator%(const texpr1+::builder &a, const texpr1+::builder &b)}{operator%(const texpr1::builder &a, const texpr1::builder &b)}}]{\setlength{\rightskip}{0pt plus 5cm}texpr1+::builder operator% (
\begin{DoxyParamCaption}
\item[{const texpr1+::builder &}]{a, }
\item[{const texpr1+::builder &}]{b}
\end{DoxyParamCaption}

The unescaped percent sign in the second argument to \texorpdfstring turns the rest of the line into a comment, leading to a LaTeX error.

[Impact]

* This bug cause FTBFS for cimg on Xenial

* This bug has been reported and conformed by Debian (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=819606)

* It has been fixed by upstream in the later version
 - https://github.com/doxygen/doxygen/commit/d59ed22f114398d74d5c3fd1445a7901d26ff93a
 - https://github.com/doxygen/doxygen/commit/d4ab02c2da7df472bebbf2724419ba00f2de229c
 - https://github.com/doxygen/doxygen/commit/537a1c67f316c5a9d2d4542e94a4ace439a78b3a

[Regression Potential]

* Regression potential is low

* The patch filters adds escapes for '&', '$', '%', '#' when generating latex documentation. The change is tiny and these changes are already in the later version

* With the patch the cimg_1.6.5+dfsg-1ubuntu0.1 documentation can build without issues

[Test Case]

* When try to build cimg_1.6.5+dfsg-1ubuntu0.1, the following error occurs:

! ==> Fatal error occurred, no output PDF file produced!
Transcript written on refman.log.
Makefile:6: recipe for target 'refman.pdf' failed
make[2]: *** [refman.pdf] Error 1
make[2]: Leaving directory '/<<BUILDDIR>>/cimg-1.6.5+dfsg/html/latex'
# autogenerated makefile lacks a final pdflatex call to get references right (that's why the above '|| true')
cd html/latex && pdflatex refman
This is pdfTeX, Version 3.14159265-2.6-1.40.16 (TeX Live 2015/Debian) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./refman.tex
LaTeX2e <2016/02/01>

[Other Info]

* The upstream discussion: https://github.com/doxygen/doxygen/issues/5962

[Daniel Wang (danielwang88)]

Backport patches