This patch corrects a problem encountered when reading the binlog from a remote
host. The application was crashing because the buffer variable (temp_buf) in 
log_event was not pointing to the incoming data. For a normal file read, this 
buffer is allocated by a previous call of read_log_event. However, when reading
from a remote host, the first call to read_log_event is not executed therefore
no buffer is allocated. Furthermore, there is no need to allocate a new buffer 
because the incoming stream is what needs to be read. 

This patch adds the call to initialize the temp_buf variable if reading from a 
remote host. It also adds a check at destroy time to ensure the temp_buf is not
freed if reading from a remote host.