Enable WinVNC build with MinGW and MinGW64


git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4723 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/common/os/os.h b/common/os/os.h
index 1847a49..f770e2b 100644
--- a/common/os/os.h
+++ b/common/os/os.h
@@ -23,6 +23,8 @@
 #include <config.h>
 #endif
 
+#include <os/w32tiger.h>
+
 /*
  * Get VNC home directory ($HOME/.vnc or %APPDATA%/vnc/).
  * If HOME environment variable is set then it is used.