patch 8.0.0492: a failing client-server request can make Vim hang

Problem:    A failing client-server request can make Vim hang.
Solution:   Add a timeout argument to functions that wait.
diff --git a/src/proto/if_xcmdsrv.pro b/src/proto/if_xcmdsrv.pro
index 137020e..801dc00 100644
--- a/src/proto/if_xcmdsrv.pro
+++ b/src/proto/if_xcmdsrv.pro
@@ -1,11 +1,11 @@
 /* if_xcmdsrv.c */
 int serverRegisterName(Display *dpy, char_u *name);
 void serverChangeRegisteredWindow(Display *dpy, Window newwin);
-int serverSendToVim(Display *dpy, char_u *name, char_u *cmd, char_u **result, Window *server, int asExpr, int localLoop, int silent);
+int serverSendToVim(Display *dpy, char_u *name, char_u *cmd, char_u **result, Window *server, int asExpr, int timeout, int localLoop, int silent);
 char_u *serverGetVimNames(Display *dpy);
 Window serverStrToWin(char_u *str);
 int serverSendReply(char_u *name, char_u *str);
-int serverReadReply(Display *dpy, Window win, char_u **str, int localLoop);
+int serverReadReply(Display *dpy, Window win, char_u **str, int localLoop, int timeout);
 int serverPeekReply(Display *dpy, Window win, char_u **str);
 void serverEventProc(Display *dpy, XEvent *eventPtr, int immediate);
 void server_parse_messages(void);