Improved GMP_CC and GMP_CFLAGS retrieval (in particular for MS Windows).
Fixed a build failure on some platforms when --with-gmp-build is used.
Bug fixes (see ChangeLog file), in particular in mpfr_div_ui, which
could yield an incorrectly rounded result to nearest when using
different precisions; this bug had been present since the introduction
of mpfr_div_ui, and in MPFR 4.0.0, it was affecting mpfr_div too.
New: optional "make check-exported-symbols", mainly for the MPFR developers
and binary distributions, to check that MPFR does not define symbols with a
GMP reserved prefix (experimental).
Changes from version 4.0.0 to version 4.0.1: