patch 7.4.1399
Problem:    The MS-DOS code does not build.
Solution:   Remove the old MS-DOS code.
diff --git a/src/buffer.c b/src/buffer.c
index 9f61eef..89dedc5 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -541,9 +541,7 @@
 {
     buf->b_ml.ml_line_count = 1;
     unchanged(buf, TRUE);
-#ifndef SHORT_FNAME
     buf->b_shortname = FALSE;
-#endif
     buf->b_p_eol = TRUE;
     buf->b_start_eol = TRUE;
 #ifdef FEAT_MBYTE
@@ -2911,9 +2909,7 @@
     }
 #endif
 
-#ifndef SHORT_FNAME
     buf->b_shortname = FALSE;
-#endif
 
     buf_name_changed(buf);
     return OK;
@@ -4480,7 +4476,7 @@
 # ifdef BACKSLASH_IN_FILENAME
 	    || strstr((char *)fname, "\\\\") != NULL
 # endif
-# if defined(MSWIN) || defined(DJGPP)
+# if defined(MSWIN)
 	    || vim_strchr(fname, '~') != NULL
 # endif
 	    )