patch 8.1.1393: unnecessary type casts

Problem:    Unnecessary type casts.
Solution:   Remove type casts from alloc() and lalloc() calls. (Mike Williams)
diff --git a/src/message.c b/src/message.c
index f1801c3..489edc3 100644
--- a/src/message.c
+++ b/src/message.c
@@ -875,7 +875,7 @@
 	(void)delete_first_msg();
 
     /* allocate an entry and add the message at the end of the history */
-    p = (struct msg_hist *)alloc((int)sizeof(struct msg_hist));
+    p = (struct msg_hist *)alloc(sizeof(struct msg_hist));
     if (p != NULL)
     {
 	if (len < 0)
@@ -2360,7 +2360,7 @@
 
     if (s > *sb_str)
     {
-	mp = (msgchunk_T *)alloc((int)(sizeof(msgchunk_T) + (s - *sb_str)));
+	mp = (msgchunk_T *)alloc(sizeof(msgchunk_T) + (s - *sb_str));
 	if (mp != NULL)
 	{
 	    mp->sb_eol = finish;