pl/math: Set fenv flags in Neon asinhf

Routine no longer relies on vector log1pf, as this has to become more
complex to deal with fenv itself. Instead we re-use a log1pf helper
from Neon atanhf which does no special-case handling, instead leaving
it all up to the main routine. We now just fall back to the scalar
routine for special-case handling. This uncovered a mistake in
asinhf's handling of NaNs, which has been fixed.
5 files changed