libavutil/rc4.c:43: error: Uninitialized Value
  The value read from state[_] was never initialized.

libavutil/rc4.c:43:9: 
41.     while (datalen-- > 0) {
42.         uint8_t sum = state[x] + state[y];
43.         FFSWAP(uint8_t, state[x], state[y]);
            ^
44.         *data++ ^= state[sum];
45.         x++;
