listen: Turn off CLIENT_MAX_WAIT_SECS

The idea behind this feature was to avoid the client thread in a listen
server getting stuck forever if the mirroring thread in the source died.
However, it breaks any sane implementation of max_Bps in that thread,
and there are lingering concerns over how it might operate under normal
conditions anyway.

Specifically, if iterating over the bitmap takes a long time, or even just
reading the requisite 8MB from the disc in order to send it, then the
5-second timeout could be hit, causing mirroring to fail unnecessarily.

src/client.h

@@ -4,6 +4,8 @@
 #include <signal.h>
 #include <time.h>
 
+#ifdef HAS_LISTEN_TIMEOUT
+
 /** CLIENT_MAX_WAIT_SECS
  * This is the length of time an inbound migration will wait for a fresh
  * write before assuming the source has Gone Away.  Note: it is *not*
@@ -12,6 +14,8 @@
  */
 #define CLIENT_MAX_WAIT_SECS 5
 
+#endif
+
 /** CLIENT_HANDLER_TIMEOUT
  * This is the length of time (in seconds) any request can be outstanding for.
  * If we spend longer than this in a request, the whole server is killed.