patch 8.0.1496: clearing a pointer takes two lines

Problem:    Clearing a pointer takes two lines.
Solution:   Add VIM_CLEAR() and replace vim_clear(). (Hirohito Higashi,
            closes #2629)
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index 73fe019..6caed87 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -1298,7 +1298,6 @@
 	if (this_due <= 1)
 	{
 	    bevalexpr_due_set = FALSE;
-
 	    if (balloonEval == NULL)
 	    {
 		balloonEval = (BalloonEval *)alloc(sizeof(BalloonEval));
@@ -5489,8 +5488,7 @@
     {
 	for (i = 0; locales[i] != NULL; i++)
 	    vim_free(locales[i]);
-	vim_free(locales);
-	locales = NULL;
+	VIM_CLEAR(locales);
     }
 }
 #  endif