Bug#737915: workaround

[Gert Wollny <gerddie@gmail.com>]

Hi, 

it seems that running Xnest with the -nocursor option is a workaround. I
didn't test it extensively, but I was able to open two screens with
xterms and copy from one to the other screen. 

I was not able to debug it on Debian, because there I didn't have debug
information available, but on my Gentoo installation I could reproduce
it and have a closer look. There it  was xnest from
xorg-xserver-1.6.4-r2, the bug report is for 1.14.5, but the bug also
persists on Debian with xnest 1.17.2-1 and the workaround was tested
with this version.

The sigsegv happens in 

hw/xnest/Cursor.c:142 

137	void
138	xnestSetCursor(DeviceIntPtr pDev, ScreenPtr pScreen, 
        CursorPtr pCursor, int x,
139	               int y)
140	{
141	    if (pCursor) {
142	        XDefineCursor(xnestDisplay,
143	                      xnestDefaultWindows[pScreen->myNum],
144	                      xnestCursor(pCursor, pScreen));
145	    }
146	}

I guess the problem is with xnestCursor which is a macro that calls a
macro and does wired things. 

With the -nocurser option Xnest still crashes when terminating the
program - but somewhere else.  

Best, 
Gert