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/sign.c b/src/sign.c
index 32e6bad..9766d4e 100644
--- a/src/sign.c
+++ b/src/sign.c
@@ -85,8 +85,7 @@
     if (HASHITEM_EMPTY(hi))
     {
 	// new group
-	group = (signgroup_T *)alloc(
-		(unsigned)(sizeof(signgroup_T) + STRLEN(groupname)));
+	group = (signgroup_T *)alloc(sizeof(signgroup_T) + STRLEN(groupname));
 	if (group == NULL)
 	    return NULL;
 	STRCPY(group->sg_name, groupname);
@@ -737,8 +736,7 @@
     int	start = next_sign_typenr;
 
     // Allocate a new sign.
-    sp = (sign_T *)alloc_clear_id((unsigned)sizeof(sign_T),
-	    aid_sign_define_by_name);
+    sp = (sign_T *)alloc_clear_id(sizeof(sign_T), aid_sign_define_by_name);
     if (sp == NULL)
 	return NULL;