gnutls_hex_encode inconsistency

[John Brooks]

Just a quick little bug here - gnutls_hex_encode, according to the documentation (and convention), will copy the output size to size_t *result_size, but does not actually do so. This leaves no way (other than manually doing the math) to get the exact output size of this function. Threw me off a little when I had a couple hundred bytes of garbage afterwards :P

Thanks,

  - John Brooks