qfsm: fix build with gcc 6 (#29245)

pkgs/applications/science/electronics/qfsm/default.nix

@@ -10,7 +10,10 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ qt4 cmake graphviz pkgconfig ];
 
-  patches = [ ./drop-hardcoded-prefix.patch ];
+  patches = [
+    ./drop-hardcoded-prefix.patch
+    ./gcc6-fixes.patch
+  ];
 
   hardeningDisable = [ "format" ];
 

pkgs/applications/science/electronics/qfsm/gcc6-fixes.patch

@@ -0,0 +1,20 @@
+--- qfsm-0.54.0-Source-orig/src/FileIO.cpp	2015-01-02 19:01:46.000000000 +0100
++++ qfsm-0.54.0-Source/src/FileIO.cpp	2017-09-11 19:53:30.579488402 +0200
+@@ -1617,7 +1617,7 @@
+   QString ext;
+ 
+   if (!imp)
+-    return FALSE;
++    return NULL;
+ 
+   Project* p=NULL;
+   importdlg->setAcceptMode(QFileDialog::AcceptOpen);
+@@ -1641,7 +1641,7 @@
+   ifstream fin(act_importfile);
+ 
+   if (!fin)
+-    return FALSE;
++    return NULL;
+ 
+   emit setWaitCursor();
+