[gtk/gtk-2-24] Visual Studio builds: Fix previous commit

[Chun-wei Fan <fanchunwei src gnome org>]

commit cd196c4f1d513095be66de5f9343423420232787
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Tue Jun 18 16:28:10 2019 +0800

    Visual Studio builds: Fix previous commit
    
    I forgot to include configure.ac in the commit, which is needed.

 configure.ac | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/configure.ac b/configure.ac
index 44d3056082..badf12d9a6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1754,6 +1754,7 @@ build/win32/vs11/Makefile
 build/win32/vs12/Makefile
 build/win32/vs14/Makefile
 build/win32/vs15/Makefile
+build/win32/vs16/Makefile
 gdk/Makefile
 gdk/x11/Makefile
 gdk/win32/Makefile