* libm/common/s_rint.c: Fix error when integral part had 18 bits and
fraction had bits set beyond first radix bit. Also, make 2-part
adjustment consistent with 1-part adjustment when adjusting fractional
bits.
* libm/common/sf_rint.c: Make fractional-bit adjustment consistent
with s_rint.c by setting 0b.01 instead of 0b.001.