Fixed a leak in the get_mpz test.
Fixed a leak in the get_mpz test.

jpflori/flint2,fredrik-johansson/flint2,wbhart/flint2,fredrik-johansson/flint2,dsroche/flint2,wbhart/flint2,jpflori/flint2,dsroche/flint2,dsroche/flint2,wbhart/flint2,dsroche/flint2,jpflori/flint2,fredrik-johansson/flint2,jpflori/flint2