[bazel][libc] Update MPFR to v4.2.2 (#156691)
Use MPFR v4.2.2 rather than MPFR v4.1.1 for Bazel/Clang builds to avoid
conflicts with glibc’s `__float128` fallback typedef. See
https://gitlab.inria.fr/mpfr/mpfr/-/commit/c37c9d599b9aced92e182507bf223440bbc9a9f1
for further details.
Fixes https://github.com/llvm/llvm-project/issues/147879
