patch 8.2.1507: using malloc() directly

Problem:    Using malloc() directly.
Solution:   Use ALLOC_ONE().  Remove superfluous typecast.  (Hussam al-Homsi,
            closes #6768)
diff --git a/src/eval.c b/src/eval.c
index cc044a4..4b1e0f1 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4352,7 +4352,8 @@
 	    }
 	    else
 	    {
-		ht_stack_T *newitem = (ht_stack_T*)malloc(sizeof(ht_stack_T));
+		ht_stack_T *newitem = ALLOC_ONE(ht_stack_T);
+
 		if (newitem == NULL)
 		    abort = TRUE;
 		else
@@ -4378,8 +4379,8 @@
 	    }
 	    else
 	    {
-		list_stack_T *newitem = (list_stack_T*)malloc(
-							sizeof(list_stack_T));
+		list_stack_T *newitem = ALLOC_ONE(list_stack_T);
+
 		if (newitem == NULL)
 		    abort = TRUE;
 		else