unsigned long long conversion

[keith.briggs at bt.com]

I have solved my own problem with this:

void mpz_set_uj(mpz_t x, unsigned long long y) {
  mpz_import(x,sizeof(unsigned long long),-1,1,0,0,&y);
}

(but I still need the mpz_add_uj and mpz_mul_uj functions.)

Keith