riched20/tests: Make sure return value is used (LLVM/Clang).

dlls/riched20/tests/editor.c

@@ -6087,7 +6087,7 @@ static void test_EM_CHARFROMPOS(void)
     hwnd = new_richedit(NULL);
     result = SendMessageA(hwnd, WM_SETTEXT, 0,
                           (LPARAM)"one two three four five six seven\reight");
-
+    ok(result == 1, "Expected 1, got %d", result);
     GetClientRect(hwnd, &rcClient);
 
     result = SendMessage(hwnd, EM_CHARFROMPOS, 0, (LPARAM)&point);