Log Message:
Update textproc/discount to discount-2.1.8a.
Patch provided by Derouiche in PR pkg/50404.

Changes:
o version 2.1.8a When I put in the patch to ..
    # Change the mail demangler to a debian-specific 'always mangle
      one way' hack. (enabled with the configure.sh option
      --debian-glitch)

  I messed up the format string and made the mangled email address
  into a fixed bogus string. Sigh. Fixed (thanks to a patch from
  Alessandro Ghedini), updated (and I really have to expand the
  runtime configuration flags array to be long enough to fit 64
  settings, but that?s a fix for a different day) and released.

o version 2.1.8 After a year or so of letting the code sit and slowly
  accumulate fixes, a new version which fixes a wad of bugs and adds
  a few new features. Some of this code is front other people, and
  those changes will be marked with their names:

    # FINALLY address the bug where markdown extra-style footnotes
      lose numbering when they show up in nested element; I was not
      carrying the m-e reference# inside the footnotes structure, but
      was instead carrying it in the parent structure and not
      updating it. So I changed the footnotes structure to include
      the reference + the list of footnotes, which made the
      misnumbering go away on my tests.
    # Fix makefile distclean to cleanup all the generated files and
      corrected the names of the installed sample program man pages
      to end in .1 (Mark Pizzolato mark@infocomm.com)
    # Change the mail demangler to a debian-specific 'always mangle
      one way' hack. (enabled with the configure.sh option
      --debian-glitch)
    # Add --with-unmangled-email compile-time flag to disable mailto:
      mangling
    # Allow the magic output filename -, which means send output to
      stdout instead of to a file.
    # Fix a bug where autolink + github flavored markdown absorbs the
      ^C eoln character into a link at the end of a line.
    # Tweak install.samples so that the user can supply a SAMPLE_PFX
      on the command line SAMPLE_PFX=discount- make install.samples
      to install the sample programs with a package-specific prefix.
    # Emit pages in utf-8 instead of us-ascii (simply a change to the
      Content-Type meta) (Nathan Phillip Brink binki@gentoo.org)
    # Patch the horrible list handler to support long numeric list
      items (George Hartzell hartzell@alerce.com)
    # Various bugfixes (Masayoshi Sekimura sekimura@gmail.com)
    # Fix support for CFLAGS=-m32 ./configure.sh by using CFLAGS for
      all build invokations of CC. (Nathan Phillip Brink
      binki@gentoo.org)
    # Github-style language attributes on fenced code blocks (Loren
      Segal lsegal@amazon.com)
    # When defining WORD & DWORD, check first for the MS Windows
      WinDef.h file; if found, include it instead of defining WORD &
      DWORD ourselves.
    # support url-encoded anchor links with --with-urlencoded-anchor
      option (Daisuke Murase typester@cpan.org)