win: open child stdio handles in overlapped-mode (#8113)

This will be used e.g. by the python client for native asyncio support

third-party/patches/libuv-overlapped.patch

@@ -0,0 +1,33 @@
+diff --git a/include/uv.h b/include/uv.h
+index cdd251d8..79b7930e 100644
+--- a/include/uv.h
++++ b/include/uv.h
+@@ -865,7 +865,8 @@ typedef enum {
+    * flags may be specified to create a duplex data stream.
+    */
+   UV_READABLE_PIPE  = 0x10,
+-  UV_WRITABLE_PIPE  = 0x20
++  UV_WRITABLE_PIPE  = 0x20,
++  UV_OVERLAPPED_PIPE = 0x40
+ } uv_stdio_flags;
+ 
+ typedef struct uv_stdio_container_s {
+diff --git a/src/win/process-stdio.c b/src/win/process-stdio.c
+index 032e3093..b53bdea7 100644
+--- a/src/win/process-stdio.c
++++ b/src/win/process-stdio.c
+@@ -131,12 +131,13 @@ static int uv__create_stdio_pipe_pair(uv_loop_t* loop,
+   sa.lpSecurityDescriptor = NULL;
+   sa.bInheritHandle = TRUE;
+ 
++  BOOL overlap = server_pipe->ipc || (flags & UV_OVERLAPPED_PIPE);
+   child_pipe = CreateFileA(pipe_name,
+                            client_access,
+                            0,
+                            &sa,
+                            OPEN_EXISTING,
+-                           server_pipe->ipc ? FILE_FLAG_OVERLAPPED : 0,
++                           overlap ? FILE_FLAG_OVERLAPPED : 0,
+                            NULL);
+   if (child_pipe == INVALID_HANDLE_VALUE) {
+     err = GetLastError();