GNU MPFR 4.2.2 Release Candidate

[sisyphus]

Hi,

LGTM with mingw-w64 ports of gcc.

(The 4.2.2-rc1 "tar.gz" had apparently not been gzipped, and therefore
didn't match the published SHA digests.
The "tar.xz" was fine. I didn't check the "tar.bz2" or the "zip".)

Cheers,
Rob