mpfr: Update to version 4.2.0p12

mpfr: Update to version 4.2.0p12

- Update from version 4.2.0p9 to 4.2.0p12
- Update of rootfile not required
- Changelog - additional patches from 10 to 12 over previous update
    10 - GCC 12 emits a spurious "may be used uninitialized" warning on tests/tfpif.c
         with -O1, and GCC 13 has the same issue also with -O2 (GCC bug 106155). This can
         make some test scripts fail for the developers. The gcc-pr106155-workaround
         patch provides a workaround for this bug in GCC.
         Corresponding changeset in the 4.2 branch: c0031f1af.
    11 - The mpfr_inp_str function does not handle the '\0' character correctly when it
         is not a whitespace character (which is almost always the case in practice, or
         really always the case). For instance, if the word is the sequence
         { '1', '\0', '2' }, the string "1" is passed to mpfr_set_str because '\0' is
         regarded as a terminating null character, and one gets a valid number (1) while
         '\0' in a word is necessarily invalid. This is fixed by the inp_str-nullchar
         patch. The testcase in the repository cannot be provided in the patch because of
         the null character in one of the files.
         Corresponding changeset in the 4.2 branch: 6a68387b2.
    12 - When '\0' is a whitespace character, i.e. when isspace(0) is true in the current
         locale (as allowed by ISO C for non-"C" locales), the mpfr_strtofr function
         regards a '\0' in the leading whitespace sequence as a whitespace. This is
         incorrect, since from the definition of a string, the first '\0' is the
         terminating null character (before the notion of whitespace is involved). In
         such locales, this is a vulnerability, because characters after the terminating
         null character are read to determine the result; however, such locales are rare
         or nonexistent (Mutt's lib.h suggests that some systems have such locales, but
         this was in 1998). This is fixed by the strtofr-nullchar patch.
         Corresponding changeset in the 4.2 branch: 964fbaa31.

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