Prevent "undefined symbol: ev_rt_now" link errors in third-party modules.

Fixes #1181.

deps/uv/ev/ev.c

@@ -730,6 +730,12 @@ typedef struct
 #else
 
   ev_tstamp ev_rt_now;
+
+  ev_tstamp ev_now (void)
+  {
+    return ev_rt_now;
+  }
+
   #define VAR(name,decl) static decl;
     #include "ev_vars.h"
   #undef VAR

deps/uv/ev/ev.h

@@ -561,13 +561,7 @@ ev_tstamp ev_now (EV_P); /* time w.r.t. timers and the eventloop, updated after
 
 int ev_default_loop (unsigned int flags EV_CPP (= 0)); /* returns true when successful */
 
-EV_INLINE ev_tstamp
-ev_now (void)
-{
-  extern ev_tstamp ev_rt_now;
-
-  return ev_rt_now;
-}
+ev_tstamp ev_now (void);
 
 /* looks weird, but ev_is_default_loop (EV_A) still works if this exists */
 EV_INLINE int