[krbdev.mit.edu #6209] Callers of krb5_encrypt_data not freeing allocated memory

[Alexandra Ellwood via RT]

obtain_sam_data (preauth.c) and pa_sam (preauth2.c) do not free the memory allocated and 
returned in the last argument to krb5_encrypt_data.  In both functions this argument is named sam_response.sam_enc_nonce_or_ts. 

I think a call to krb5_free_sam_response_contents is missing somewhere...

(Found using leak checker)