tools/mpfr: update to 4.2.1
Changes from version 4.2.0 to version 4.2.1:
- Bug fixes (see <https://www.mpfr.org/mpfr-4.2.0/#fixed> and/or the
ChangeLog file).
- Improved MPFR manual.
- Configure tests: replaced the test of the link with GMP, in order to
avoid the use of a function without a prototype (Autoconf issue), as
this is obsolescent in ISO C. The new test should be more robust.
Signed-off-by: Linhui Liu <[email protected]>
Linhui Liu