libuv: darwin: group kqueue-specific definitions together

Utilities/cmlibuv/include/uv/darwin.h

@@ -30,6 +30,8 @@
 # define UV_PLATFORM_SEM_T semaphore_t
 #endif
 
+#define UV_HAVE_KQUEUE 1
+
 #define UV_IO_PRIVATE_PLATFORM_FIELDS                                         \
   int rcount;                                                                 \
   int wcount;                                                                 \
@@ -56,6 +58,4 @@
 #define UV_STREAM_PRIVATE_PLATFORM_FIELDS                                     \
   void* select;                                                               \
 
-#define UV_HAVE_KQUEUE 1
-
 #endif /* UV_DARWIN_H */