Under some circumstances, clients could cause SIGPIPE to slcl. Since
this signal was not handled by server.c (i.e., via sigaction(3)), slcl
would crash without any error messages printed to stderr.
In such situation, SIGPIPE should not be usually considered a fatal
error, so it is preferrable to close the connection and keep working.
select(2) has a number of well-known issues (e.g.: FD_SETSIZE limiting
the maximum amount of file descriptors to watch) that are mostly solved
by poll(2) and thus can be used as a drop-in replacement.
According to C99 §7.20.3.4:
If memory for the new object cannot be allocated, the old object is not
deallocated and its value is unchanged.
Therefore, a temporary pointer must be used to ensure the original
object can still be deallocated should realloc(3) return a null pointer.