src: remove unused uv.h include in async-wrap.h

I cannot find any usage of uv in the header and think that it can be
removed.

PR-URL: nodejs#12973
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: danbev

src/async-wrap.h

@@ -25,7 +25,6 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include "base-object.h"
-#include "uv.h"
 #include "v8.h"
 
 #include <stdint.h>