[x265] [PATCH 5 of 5] cli: report errors from registering signal handler

[SF Markus Elfring]

> +        cliopt.log(X265_LOG_ERROR, "Unable to register CTRL+C handler, error %d\n", errno);

How do you think about to retrieve a message text for the passed error code?
Would you like to call the function "strerror" there (and similar source 
code places)?
http://pubs.opengroup.org/onlinepubs/9699919799/functions/strerror.html

Regards,
Markus