Function fiat_crypto::poly1305_64::fiat_poly1305_opp

pub fn fiat_poly1305_opp(
    out1: &mut fiat_poly1305_loose_field_element,
    arg1: &fiat_poly1305_tight_field_element
)

The function fiat_poly1305_opp negates a field element.

Postconditions: eval out1 mod m = -eval arg1 mod m