Use a better size for vfd_socket_t on windows, and make sure to pass the VFD object to the watcher.

src/gevent/libev/corecext.ppyx

@@ -810,7 +810,7 @@ cdef public class io(watcher) [object PyGeventIOObject, type PyGeventIO_Type]:
             raise ValueError('illegal event mask: %r' % events)
         # All the vfd_functions are no-ops on POSIX
         cdef int vfd = libev.vfd_open(fd)
-        libev.ev_io_init(&self._watcher, <void *>gevent_callback_io, fd, events)
+        libev.ev_io_init(&self._watcher, <void *>gevent_callback_io, vfd, events)
         self.__watcher = <libev.ev_watcher*>&self._watcher
 
     def __dealloc__(self):

src/gevent/libev/libev.pxd

+# From cython/includes/libc/stdint.pxd
+# Longness only used for type promotion.
+# Actual compile time size used for conversions.
+
+# 7.18 Integer types <stdint.h>
+cdef extern from "<stdint.h>" nogil:
+
+    # 7.18.1.4 Integer types capable of holding object pointers
+    ctypedef ssize_t intptr_t
+
 cdef extern from "libev_vfd.h":
 # cython doesn't process pre-processor directives, so they
 # don't matter in this file. It just takes the last definition it sees.
-    ctypedef long long vfd_socket_t
+    ctypedef intptr_t vfd_socket_t
 
     long vfd_get(int)
     int vfd_open(long) except -1
     void vfd_free(int)
 
-cdef extern from "libev.h":
+cdef extern from "libev.h" nogil:
     int EV_MINPRI
     int EV_MAXPRI
 

src/gevent/libev/libev_vfd.h

 #ifdef _WIN32
-
-# ifdef _WIN64
-typedef PY_LONG_LONG vfd_socket_t;
-# define vfd_socket_object PyLong_FromLongLong
-# else /* _WIN32 && !_WIN64 */
-typedef long vfd_socket_t;
-# define vfd_socket_object PyInt_FromLong
-
-#endif /* _WIN64 */
+/* see discussion in the libuv directory: this is a SOCKET which is a
+   HANDLE which is a PVOID (even though they're really small ints),
+   and CPython and PyPy return that SOCKET cast to an int from
+   fileno()
+*/
+typedef intptr_t vfd_socket_t;
+#define vfd_socket_object PyLong_FromLongLong
 
 #ifdef LIBEV_EMBED
 /*