libquadmath: Assorted libquadmath strtoflt128 fixes [PR87204, PR94756]

libquadmath: Assorted libquadmath strtoflt128 fixes [PR87204, PR94756]

This patch cherry-pickx 8 commits from glibc which fix various strtod_l
bugs.  Additionally, it makes mp_limb_t 64-bit on llp64 targets like
64-bit cygwin.

2023-03-03  niXman  <i.nixman@autistici.org>
	    Jakub Jelinek  <jakub@redhat.com>

	PR libquadmath/87204
	PR libquadmath/94756
	* printf/gmp-impl.h (mp_limb_t, mp_limb_signed_t, BITS_PER_MP_LIMB):
	Use 64-bit limbs on LLP64 targets.
	* strtod/strtod_l.c (round_and_return): Cherry-pick glibc
	9310c284ae9 BZ #16151, 4406c41c1d6 BZ #16965 and fcd6b5ac36a
	BZ #23279 fixes.
	(____STRTOF_INTERNAL): Cherry-pick glibc b0debe14fcf BZ #23007,
	5556d30caee BZ #18247, 09555b9721d and c6aac3bf366 BZ #26137 and
	d84f25c7d87 fixes.