patch 8.2.0967: unnecessary type casts for vim_strnsave()

Problem:    Unnecessary type casts for vim_strnsave().
Solution:   Remove the type casts.
diff --git a/src/menu.c b/src/menu.c
index b017925..8a69edd 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -1810,7 +1810,7 @@
     {
 	if (actext != NULL)
 	    *actext = vim_strsave(p + 1);
-	text = vim_strnsave(str, (int)(p - str));
+	text = vim_strnsave(str, p - str);
     }
     else
 	text = vim_strsave(str);
@@ -2716,7 +2716,7 @@
 		if (from != NULL)
 		{
 		    from_noamp = menu_text(from, NULL, NULL);
-		    to = vim_strnsave(to, (int)(arg - to));
+		    to = vim_strnsave(to, arg - to);
 		    if (from_noamp != NULL && to != NULL)
 		    {
 			menu_translate_tab_and_shift(from);