This patch fixes SLiM so it really waits for the X server to be ready
before attempting to connect to it.  Indeed, the X server notices that
its parent process has a handler for SIGUSR1, and consequently sends it
SIGUSR1 when it's ready to accept connections.

The problem was that SLiM doesn't pay attention to SIGUSR1.  So in practice,
if X starts slowly, then SLiM gets ECONNREFUSED a couple of time on
/tmp/.X11-unix/X0, then goes on trying to connect to localhost:6000,
where nobody answers; eventually, it times out and tries again on
/tmp/.X11-unix/X0, and finally it shows up on the screen.

Patch by L. Courtès.

--- slim-1.3.6/app.cpp	2014-02-05 15:27:20.000000000 +0100
+++ slim-1.3.6/app.cpp	2014-02-09 22:42:04.000000000 +0100
@@ -119,7 +119,9 @@ void CatchSignal(int sig) {
 	exit(ERR_EXIT);
 }
 
+static volatile int got_sigusr1 = 0;
 void User1Signal(int sig) {
+	got_sigusr1 = 1;
 	signal(sig, User1Signal);
 }
 
@@ -884,6 +886,7 @@ int App::WaitForServer() {
 	int	ncycles	 = 120;
 	int	cycles;
 
+	while (!got_sigusr1);
 	for(cycles = 0; cycles < ncycles; cycles++) {
 		if((Dpy = XOpenDisplay(DisplayName))) {
 			XSetIOErrorHandler(xioerror);