Insufficient randomness in generation of DNS query IDs

When /dev/urandom or RtlGenRandom() are unavailable, c-ares uses rand() to generate random numbers used for DNS query ids. This is not a CSPRNG, and it is also not seeded by srand() so will generate predictable output.
Input from the random number generator is fed into a non-compilant RC4 implementation and may not be as strong as the original RC4 implementation.
No attempt is made to look for modern OS-provided CSPRNGs like arc4random() that is widely available.