Remove the cap on epoll events

Currently the code will silently blank out events if there are more
then 512 epoll events, causing them never to be handled at all. This
patch removes the cap on the number of events for epoll_wait, thereby
avoiding this issue.

(cherry picked from commit 1c724e9e0e)

src/libsystemd/sd-event/sd-event.c

@@ -37,7 +37,6 @@
 
 #include "sd-event.h"
 
-#define EPOLL_QUEUE_MAX 512U
 #define DEFAULT_ACCURACY_USEC (250 * USEC_PER_MSEC)
 
 typedef enum EventSourceType {
@@ -2367,7 +2366,7 @@ _public_ int sd_event_wait(sd_event *e, uint64_t timeout) {
                 return 1;
         }
 
-        ev_queue_max = CLAMP(e->n_sources, 1U, EPOLL_QUEUE_MAX);
+        ev_queue_max = MAX(e->n_sources, 1u);
         ev_queue = newa(struct epoll_event, ev_queue_max);
 
         m = epoll_wait(e->epoll_fd, ev_queue, ev_queue_max,