MINOR: mworker: don't deinit the poller fd when in wait mode

If haproxy failed to load its configuration, the process is reexecuted
and it did not init the poller. So we must not try to deinit the poller
before the exec().
diff --git a/src/haproxy.c b/src/haproxy.c
index 1fa1d3c..9dfdf9b 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -666,7 +666,8 @@
 		next_argv[next_argc++] = NULL;
 	}
 
-	deinit_pollers(); /* we don't want to leak the poller fd */
+	if (getenv("HAPROXY_MWORKER_WAIT_ONLY") == NULL)
+		deinit_pollers(); /* we don't want to leak the poller fd */
 
 	ha_warning("Reexecuting Master process\n");
 	execvp(next_argv[0], next_argv);