mpfr: Update to version 4.2.2

mpfr: Update to version 4.2.2

- Update from version 4.2.1 to 4.2.2
- Update of rootfile
- Changelog
    4.2.2
	- In order to resolve a portability issue with the _Float128 fallback to
	  __float128 for binary128 support (e.g. with Clang and glibc 2.41), the
	  prototypes of the corresponding conversion functions had to be changed,
	  with _Float128 replaced by mpfr_float128, where mpfr_float128 is a macro
	  defined as _Float128 by default. This changes neither the ABI nor the API
	  (except that the end user of MPFR would need to define mpfr_float128 as
	  the actual type for the binary128 format if this is not the standard
	  _Float128 type).
	- Other bug fixes (see <https://www.mpfr.org/mpfr-4.2.1/#fixed> and/or the
	  ChangeLog file). In particular, the formatted output functions behaved
	  incorrectly with %c on the value 0; such a use is uncommon, but this bug
	  may have security implications.
	- Improved MPFR manual.
	- Detect the use of GMP's buggy vsnprintf replacement at configure time.
	  With it, the tests of "%a" will be disabled to avoid an assertion failure
	  in the MPFR testsuite. A warning will be displayed in the configure output
	  in such a case.
	Also, note that due to new tests related to the fix of the formatted
	  output functions with %c on the value 0, failures in the tfprintf and
	  tsprintf tests may be observed if GMP has been built with its vsnprintf
	  replacement (i.e. if GMP detected at configure time that the vsnprintf
	  function from the C library is buggy/non-conforming). This is due to a
	  bug in the vsnprintf replacement from GMP 6.3.0 (official tarball) and
	  below. This could be observed on MS Windows and OpenBSD. To get rid of
	  these failures, either use a fixed version (recommended!) or build the
	  MPFR tests with the MPFR_TESTS_SKIP_CHECK_NULL macro defined.
	  See the INSTALL file for other details.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>