libsnark: Use mp_limb_t cast instead of uint64_t when masking bigint.data

src/snark/libsnark/algebra/fields/fp.tcc

@@ -690,7 +690,7 @@ Fp_model<n, modulus> Fp_model<n,modulus>::random_element() /// returns random el
             const std::size_t part = bitno/GMP_NUMB_BITS;
             const std::size_t bit = bitno - (GMP_NUMB_BITS*part);
 
-            r.mont_repr.data[part] &= ~(UINT64_C(1)<<bit);
+            r.mont_repr.data[part] &= ~(((mp_limb_t) 1)<<bit);
 
             bitno--;
         }

src/snark/libsnark/algebra/fields/fp12_2over3over2.tcc

@@ -348,7 +348,7 @@ Fp12_2over3over2_model<n, modulus> Fp12_2over3over2_model<n,modulus>::cyclotomic
                 res = res.cyclotomic_squared();
             }
 
-            if (exponent.data[i] & (UINT64_C(1)<<j))
+            if (exponent.data[i] & (((mp_limb_t) 1)<<j))
             {
                 found_one = true;
                 res = res * (*this);