patch 9.0.1391: "clear" macros are not always used

Problem:    "clear" macros are not always used.
Solution:   Use ALLOC_ONE, VIM_CLEAR, CLEAR_POINTER and CLEAR_FIELD in more
            places. (Yegappan Lakshmanan, closes #12104)
diff --git a/src/gui_w32.c b/src/gui_w32.c
index 206645a..7a12032 100644
--- a/src/gui_w32.c
+++ b/src/gui_w32.c
@@ -8387,7 +8387,7 @@
     TOOLINFOW	*pti;
     RECT	rect;
 
-    pti = alloc(sizeof(TOOLINFOW));
+    pti = ALLOC_ONE(TOOLINFOW);
     if (pti == NULL)
 	return;
 
@@ -8655,7 +8655,7 @@
 
 // TODO: at the moment, this is just a copy of test_gui_mouse_event.
 // But, we could instead generate actual Win32 mouse event messages,
-// ie. to make it consistent wih test_gui_w32_sendevent_keyboard.
+// ie. to make it consistent with test_gui_w32_sendevent_keyboard.
     static int
 test_gui_w32_sendevent_mouse(dict_T *args)
 {