Fix compiler warning on Windows 64-bit: explicit cast size_t to unsigned long

Modules/_randommodule.c

@@ -179,7 +179,7 @@ init_by_array(RandomObject *self, unsigned long init_key[], size_t key_length)
     k = (N>key_length ? N : key_length);
     for (; k; k--) {
         mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
-                 + init_key[j] + j; /* non linear */
+                 + init_key[j] + (unsigned long)j; /* non linear */
         mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
         i++; j++;
         if (i>=N) { mt[0] = mt[N-1]; i=1; }
@@ -187,7 +187,7 @@ init_by_array(RandomObject *self, unsigned long init_key[], size_t key_length)
     }
     for (k=N-1; k; k--) {
         mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
-                 - i; /* non linear */
+                 - (unsigned long)i; /* non linear */
         mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
         i++;
         if (i>=N) { mt[0] = mt[N-1]; i=1; }