Log Message:
libidn2: Update to 2.2.0

Version 2.2.0 (released 2019-05-23)

* Perform A-Label roundtrip for lookup functions by default
* Stricter check of input to punycode decoder
* Fix punycode decoding with no ASCII chars but given delimiter
* Fix 'idn2 --no-tr64' (was a no-op)
* Allow _ as a basic code point in domain labels
* Fail building documentatino if 'ronn' isn't installed
* git tag changed to reflect https://semver.org/

Version 2.1.1 (released 2019-02-08)

* Revert SONAME bump from release 2.1.0
* Fix NULL dereference in idn2_register_u8() and idn2_register_ul()
* Fix free of random value in idn2_to_ascii_4i()
* Improved fuzzer (which found the above issues)
* Fix printf() crash in test-lookup.c on Solaris
* Check for valid unicode input in punycode encoder
* Avoid excessive CPU usage in punycode encoding with
  large inputs
* Deprecate idn2_to_ascii_4i() in favor of idn2_to_ascii_4i2()
* Restrict output length of idn2_to_ascii_4i() to 63 bytes

Version 2.1.0 (released 2019-01-04)

* Two exposed functions are no longer exposed:
  _idn2_punycode_encode() and _idn2_punycode_decode() which were
  meant to be used internally only. The output needs additional
  checks to be used safely.
  This is the reason to for the SONAME bump, just in case.
* Fix label length check for idn2_register_u8()
* Remove compiler warnings
* Use gnulib-python tool for bootstrapping if possible
* Improve build system (several small issues)
* Add missing error messages to idn2_strerror_name()
* Improve docs and remove typos
* Update gnulib