core: add bunch of EV_ constants in LIBEV_EMBED mode

gevent/core.ppyx

@@ -985,3 +985,16 @@ def set_exc_info(object type, object value):
         Py_INCREF(<PyObjectPtr>value)
         tstate.exc_value = <PyObjectPtr>value
     tstate.exc_traceback = NULL
+
+
+#ifdef LIBEV_EMBED
+EV_USE_FLOOR = libev.EV_USE_FLOOR
+EV_USE_CLOCK_SYSCALL = libev.EV_USE_CLOCK_SYSCALL
+EV_USE_REALTIME = libev.EV_USE_REALTIME
+EV_USE_MONOTONIC = libev.EV_USE_MONOTONIC
+EV_USE_NANOSLEEP = libev.EV_USE_NANOSLEEP
+EV_USE_INOTIFY = libev.EV_USE_INOTIFY
+EV_USE_SIGNALFD = libev.EV_USE_SIGNALFD
+EV_USE_EVENTFD = libev.EV_USE_EVENTFD
+EV_USE_4HEAP = libev.EV_USE_4HEAP
+#endif

gevent/libev.pxd

@@ -10,6 +10,23 @@ cdef extern from "libev.h":
     int EV_VERSION_MAJOR
     int EV_VERSION_MINOR
 
+    int EV_USE_FLOOR
+    int EV_USE_CLOCK_SYSCALL
+    int EV_USE_REALTIME
+    int EV_USE_MONOTONIC
+    int EV_USE_NANOSLEEP
+    int EV_USE_SELECT
+    int EV_USE_POLL
+    int EV_USE_EPOLL
+    int EV_USE_KQUEUE
+    int EV_USE_PORT
+    int EV_USE_INOTIFY
+    int EV_USE_SIGNALFD
+    int EV_USE_EVENTFD
+    int EV_USE_4HEAP
+    int EV_USE_IOCP
+    int EV_SELECT_IS_WINSOCKET
+
     int EV_UNDEF
     int EV_NONE
     int EV_READ