Bug#811648: FTBFS with GCC 6: cannot convert x to y

[Gert Wollny <gw.fossdev@gmail.com>]

Control: tags -1 patch 

Hi, 

attached is a patch that fixes the according build failure. 

Regarding maintainership, I'll have to test the program first to see
whether it is of any interest to me to maintain it (Upstream seems to
be dead).

Best, 
Gert 

Author: Gert Wollny <gw.fossdev@gmail.com>
Date: 2016-06-27
Description: Correct compilation with g++-6
Bug: https://bugs.debian.org/811648

--- a/Fileio.cpp
+++ b/Fileio.cpp
@@ -854,7 +854,7 @@
 
 	if(Notary || !g) {
 		ErrorBox("Output pending or\nno graph.");
-		return false;
+		return NULL;
 		}
 	cObsW = 0;				iFile = -1;
 	cbOut = sizeOut = 0;	ptr = 0L;