crt/stdio: Ensure `__pformat_intarg_t exponent` is fully initialized

Previously, `__pformat_emit_efloat()` initialized only its lower 8 bytes. If
the CRT was configured with `--enable-experimental=printf128`, the higher 8
bytes were indeterminate.

This error was observed in one of GCC's self tests, where something such as
`printf("%g\n", (float)123456789);` gave incorrect results like
`1.23457e+773810688247020537949736540986933256`.

Signed-off-by: LIU Hao <lh_mouse@126.com>
1 file changed