mpfr: upgrade 4.1.0 -> 4.1.1

Changelog:
=========
- Bug fixes (see <https://www.mpfr.org/mpfr-4.1.0/#fixed

> and/or the
  ChangeLog file), in particular for macros implementing functions.
- Improved manual formatting.

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit f733eddc)
Signed-off-by: Steve Sakoman <steve@sakoman.com>