Update libev to 4.22 (#854)

libev/Changes

@@ -14,6 +14,16 @@ TODO: embed watchers need updating when fd changes
 TODO: document portability requirements for atomic pointer access
 TODO: document requirements for function pointers and calling conventions.
 
+4.22 Sun Dec 20 22:11:50 CET 2015
+	- when epoll detects unremovable fds in the fd set, rebuild
+          only the epoll descriptor, not the signal pipe, to avoid
+          SIGPIPE in ev_async_send. This doesn't solve it on fork,
+          so document what needs to be done in ev_loop_fork
+          (analyzed by Benjamin Mahler).
+	- remove superfluous sys/timeb.h include on win32
+          (analyzed by Jason Madden).
+        - updated libecb.
+
 4.20 Sat Jun 20 13:01:43 CEST 2015
 	- prefer noexcept over throw () with C++ 11.
         - update ecb.h due to incompatibilities with c11.