patch 8.2.4241: some type casts are redundant

Problem:    Some type casts are redundant.
Solution:   Remove the type casts. (closes #9643)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 411d332..045e544 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -7158,7 +7158,7 @@
 		    break;
 	    }
 
-	    match = vim_regexec_nl(&regmatch, str, (colnr_T)startcol);
+	    match = vim_regexec_nl(&regmatch, str, startcol);
 
 	    if (match && --nth <= 0)
 		break;
@@ -7944,7 +7944,7 @@
     list->lv_u.mat.lv_idx_item = NULL;
     for (i = start; stride > 0 ? i <= end : i >= end; i += stride)
     {
-	if (list_append_number(list, (varnumber_T)i) == FAIL)
+	if (list_append_number(list, i) == FAIL)
 	    break;
 	if (list->lv_lock & VAR_ITEMS_LOCKED)
 	    list->lv_u.mat.lv_last->li_tv.v_lock = VAR_LOCKED;
@@ -9804,7 +9804,7 @@
 
     if (!transerr && lnum >= 1 && lnum <= curbuf->b_ml.ml_line_count
 	    && col >= 0 && col < (long)STRLEN(ml_get(lnum)))
-	id = syn_get_id(curwin, lnum, (colnr_T)col, trans, NULL, FALSE);
+	id = syn_get_id(curwin, lnum, col, trans, NULL, FALSE);
 #endif
 
     rettv->vval.v_number = id;
@@ -10024,7 +10024,7 @@
 	    && col >= 0 && col <= (long)STRLEN(ml_get(lnum))
 	    && rettv_list_alloc(rettv) != FAIL)
     {
-	(void)syn_get_id(curwin, lnum, (colnr_T)col, FALSE, NULL, TRUE);
+	(void)syn_get_id(curwin, lnum, col, FALSE, NULL, TRUE);
 	for (i = 0; ; ++i)
 	{
 	    id = syn_get_stack_item(i);