patch 7.4.1008
Problem:    The OS/2 code pollutes the source while nobody uses it these days.
Solution:   Drop the support for OS/2.
diff --git a/src/ui.c b/src/ui.c
index 5438a38..f622f04 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -1772,7 +1772,7 @@
 fill_input_buf(exit_on_error)
     int	exit_on_error UNUSED;
 {
-#if defined(UNIX) || defined(OS2) || defined(VMS) || defined(MACOS_X_UNIX)
+#if defined(UNIX) || defined(VMS) || defined(MACOS_X_UNIX)
     int		len;
     int		try;
     static int	did_read_something = FALSE;
@@ -1796,7 +1796,7 @@
 	return;
     }
 #endif
-#if defined(UNIX) || defined(OS2) || defined(VMS) || defined(MACOS_X_UNIX)
+#if defined(UNIX) || defined(VMS) || defined(MACOS_X_UNIX)
     if (vim_is_input_buf_full())
 	return;
     /*
@@ -1940,9 +1940,9 @@
 	    ++inbufcount;
 	}
     }
-#endif /* UNIX or OS2 or VMS*/
+#endif /* UNIX or VMS*/
 }
-#endif /* defined(UNIX) || defined(FEAT_GUI) || defined(OS2)  || defined(VMS) */
+#endif /* defined(UNIX) || defined(FEAT_GUI) || defined(VMS) */
 
 /*
  * Exit because of an input read error.