The ldbl-128ibm implementation of nextafterl / nexttowardl returns -0
in FE_DOWNWARD mode when taking the next value below the least
positive subnormal, when it should return +0. This patch fixes it to
check explicitly for this case.
Tested for powerpc.
[BZ #19678]
* sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c (__nextafterl):
Ensure +0.0 is returned when taking the next value below the least
positive value.
7b428e744b