Log Message:
re2c: update to 2.1.1.

2.1.1 (2021-03-27)
~~~~~~~~~~~~~~~~~~

- Added missing CMakeLists.txt to release tarballs
  (`#346 <https://github.com/skvadrik/re2c/issues/346>`_).

2.1 (2021-03-26)
~~~~~~~~~~~~~~~~

- Added GitHub Actions CI for Linux, macOS and Windows and fixed numerous build
  issues on those platforms (thanks to
  `Serghei Iakovlev <https://github.com/sergeyklay>`_).

- Added benchmarks for submatch extraction in lexer generators (ragel vs.
  kleenex vs. re2c with TDFA(0), TDFA(1) or sta-DFA algorithms).

  + New Autotools (configure) options: ``--enable-benchmarks``,
    ``--enable-benchmarks-regenerate``

  + New CMake options: ``-DRE2C_BUILD_BENCHMARKS``, ``-DRE2C_REGEN_BENCHMARKS``

  + New `json2pgfplot.py
    <https://github.com/skvadrik/re2c/blob/master/benchmarks/json2pgfplot.py>`_
    script that converts benchmark results in JSON to a PDF with bar charts

- Added option ``--depfile <filename>`` to generate build dependency files
  (allows to track ``/*!include:re2c*/`` dependencies in the build system).

- Added option ``--fixed-tags <none | all | toplevel>`` and improved fixed-tag
  optimization to work with nested tags.

- Added lzip to the distribution tarballs.

- Added registerless-TDFA algorithm in the experimental libre2c library.

- Explicitly disallowed invalid configuration when ``-f``, ``--storable-state``
  option is used, but ``YYFILL`` is disabled
  (`#306 <https://github.com/skvadrik/re2c/issues/306>`_).

- Fixed bug in UTF-8 decode for 4-bytes rune
  (`#307 <https://github.com/skvadrik/re2c/pull/307>`_, thanks to
  `Satoshi Yasushima <https://github.com/s-yasu>`_).

- Fixed bugs in rare cases of the end-of-input rule ``$`` usage
  (`277f0295 \ 
<https://github.com/skvadrik/re2c/commit/277f0295fc77a2dad3b9838e45f787319b54a25f>`_,
  `68611a57 \ 
<https://github.com/skvadrik/re2c/commit/68611a57a9683c05801255b35ba6217b91391dd8>`_
  and `a9d582f9 \ 
<https://github.com/skvadrik/re2c/commit/a9d582f9d2a6d123aa55f3b8b73076aae7cb5616>`_).

- Optimized ``--skeleton`` generation time.

- Renamed internal option ``--dfa`` to ``--nested-negative-tags``.

- Updated documentation for end of input handling and submatch extraction.