Now we define FMAXNUM and FMINNUM as IEEE754-2008 with +0.0>-0.0. MIPSr6's fmax/fmin just follow this rules full. FMAXNUM_IEEE and FMINNUM_IEEE will be removed in future once: 1. Fixes FMAXNUM/FMINNUM for all targets 2. The use of FMAXNUM_IEEE/FMINNUM_IEEE are not used by middle end anymore.