Fix ecc_fast: ecdsa sometimes uses mpz from gmpy2
Fix ecc_fast: ecdsa sometimes uses mpz from gmpy2

Sometimes the ints are not ints, but rather the 'mpz' type from gmpy2.
We added a workaround for this to support whatever ecdsa is doing under
the hood.

fyookball/electrum,fyookball/electrum,fyookball/electrum