[os2]: Implement pipe_has_data procedure

core/os/os2/pipe_windows.odin

@@ -15,3 +15,15 @@ _pipe :: proc() -> (r, w: ^File, err: Error) {
 	return new_file(uintptr(p[0]), ""), new_file(uintptr(p[1]), ""), nil
 }
 
+@(require_results)
+_pipe_has_data :: proc(r: ^File) -> (ok: bool, err: Error) {
+	if r == nil || r.impl == nil {
+		return false, nil
+	}
+	handle := win32.HANDLE((^File_Impl)(r.impl).fd)
+	bytes_available: u32
+    if !win32.PeekNamedPipe(handle, nil, 0, nil, &bytes_available, nil) {
+        return false, _get_platform_error()
+    }
+    return bytes_available > 0, nil
+}