patch 8.1.2422: "make depend" does not work correctly for libvterm

Problem:    "make depend" does not work correctly for libvterm.
Solution:   Fix build dependencies. And a few minor improvements.
diff --git a/src/main.c b/src/main.c
index ddb8e38..72e51a3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2939,10 +2939,10 @@
     }
 }
 
-    /*
-     * If opened more than one window, start editing files in the other
-     * windows.  make_windows() has already opened the windows.
-     */
+/*
+ * If opened more than one window, start editing files in the other
+ * windows.  make_windows() has already opened the windows.
+ */
     static void
 edit_buffers(
     mparm_T	*parmp,