patch 8.2.3914: various spelling mistakes in comments

Problem:    Various spelling mistakes in comments.
Solution:   Fix the mistakes. (Dominique Pellé, closes #9416)
diff --git a/src/window.c b/src/window.c
index 4ee75c1..ca35e5b 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1555,7 +1555,7 @@
 
     if (vertical)
     {
-	// Each windows needs at least 'winminwidth' lines and a separator
+	// Each window needs at least 'winminwidth' lines and a separator
 	// column.
 	maxcount = (curwin->w_width + curwin->w_vsep_width
 					     - (p_wiw - p_wmw)) / (p_wmw + 1);
@@ -2109,7 +2109,7 @@
 	    room = height - m;
 	    if (room < 0)
 	    {
-		// The room is less then 'winheight', use all space for the
+		// The room is less than 'winheight', use all space for the
 		// current window.
 		next_curwin_size = p_wh + room;
 		room = 0;