patch 7.4.1399
Problem:    The MS-DOS code does not build.
Solution:   Remove the old MS-DOS code.
diff --git a/src/undo.c b/src/undo.c
index 27e2218..2bf815b 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -641,9 +641,9 @@
 	u_getbot();
     }
 
-#if !defined(UNIX) && !defined(DJGPP) && !defined(WIN32) && !defined(__EMX__)
+#if !defined(UNIX) && !defined(WIN32) && !defined(__EMX__)
 	/*
-	 * With Amiga and MSDOS 16 bit we can't handle big undo's, because
+	 * With Amiga we can't handle big undo's, because
 	 * then u_alloc_line would have to allocate a block larger than 32K
 	 */
     if (size >= 8000)