Disable timerfd/signalfd on openvz, it seems broken

(imported from libratbox r27395 by nenolod)
(cherry picked from commit 21acd09)

libratbox/src/epoll.c

@@ -254,6 +254,7 @@ rb_epoll_supports_event(void)
 	/* try to detect at runtime if everything we need actually works */
 	timer_t timer;
 	struct sigevent ev;
+	struct stat st;
 	int fd;
 	sigset_t set;
 
@@ -262,6 +263,13 @@ rb_epoll_supports_event(void)
 	if(can_do_event == -1)
 		return 0;
 
+	/* Check for openvz..it has a broken timerfd.. */
+	if(stat("/proc/user_beancounters", &st) == 0)
+	{
+		can_do_event = -1;
+		return 0;
+	}
+
 #ifdef USE_TIMERFD_CREATE
 	if((fd = timerfd_create(CLOCK_REALTIME, 0)) >= 0)
 	{