Make Quiet NaN
Creates a quiet NaN of the specified precision, with a positive sign and zero payload.
_Decimal32 __d32_qNaN (void); _Decimal64 __d64_qNaN (void); _Decimal128 __d128_qNaN (void);
_Decimal32 __d32_qNaN (void);
_Decimal64 __d64_qNaN (void);
_Decimal128 __d128_qNaN (void);