Classify hexadecimal strtod and wcstod input from its own digits rather
than a long double approximation. As measured on God of War Ragnarok's
bundled libc.prx, ERANGE is set only on overflow or when the exact value
is below 2^-1074, and a value between 2^-1075 and 2^-1074 becomes the
smallest subnormal only from 2^-1075 * (1 + 2^-52) up.
Refs #9691
Co-Authored-By: Claude Opus 5.5 <[email protected]>
