Function fiat_crypto::poly1305_64::fiat_poly1305_carry

pub fn fiat_poly1305_carry(
    out1: &mut fiat_poly1305_tight_field_element,
    arg1: &fiat_poly1305_loose_field_element
)

The function fiat_poly1305_carry reduces a field element.

Postconditions: eval out1 mod m = eval arg1 mod m