patch 8.1.1230: a lot of code is shared between vim.exe and gvim.exe

Problem:    A lot of code is shared between vim.exe and gvim.exe.
Solution:   Optionally put the shared code in vim.dll. (Ken Takata,
            closes #4287)
diff --git a/src/fileio.c b/src/fileio.c
index 22a735f..b301846 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -792,7 +792,10 @@
 	    if (!is_not_a_term())
 	    {
 #ifndef ALWAYS_USE_GUI
-		mch_msg(_("Vim: Reading from stdin...\n"));
+# ifdef VIMDLL
+		if (!gui.in_use)
+# endif
+		    mch_msg(_("Vim: Reading from stdin...\n"));
 #endif
 #ifdef FEAT_GUI
 		/* Also write a message in the GUI window, if there is one. */