Fix signal handler

[elfring]

The function "LOG_PRINT" does not belong to the list of async-signal-safe functions.
I guess that a different program design will be needed for your function "sighandler".

[buaazp]

OK I see. I will try another way to process logs in future.

[buaazp]

Using async-signal-safe functions in log_handler instead of log_printf0().
Changes like redis: redis/redis#213

[elfring]

I wonder a bit about the references to Redis in this update. I find two statements also inappropriate in your function "sighandler".

[buaazp]

Thanks very much.
@elfring Do you mean fprintf() and exit() ? I have removed them in the latest commit.
And strcat() is safe. More infomation:
http://austingroupbugs.net/view.php?id=692#c1609

[elfring]

Would you like to achieve a program termination there?

[buaazp]

Yes, the signal handler here just hooks termination signals.

[elfring]

Thanks for your small source code improvement.