non-blocking processing

[Peter Kümmel]

After two failed attempts to unblock LyX while processing large files I wanna 
try it again.
But first I wanna be shoure we can use QProcess instead of the system call,
if this works the rest wouldn't be critical.

Could someone please test attached patch in his daily work?

Peter

Index: src/support/Systemcall.cpp
===================================================================
--- src/support/Systemcall.cpp  (revision 29511)
+++ src/support/Systemcall.cpp  (working copy)
@@ -18,6 +18,8 @@
 
 #include <cstdlib>
 
+#include <QProcess>
+
 using namespace std;
 
 namespace lyx {
@@ -39,6 +41,15 @@
                }
        }
 
+//#define DISABLE_EVALUATE_QPROCESS
+#ifndef DISABLE_EVALUATE_QPROCESS
+       QString cmd = QString::fromLocal8Bit(command.c_str());
+       QProcess process;
+       process.start(cmd);
+       process.waitForFinished();
+       return process.exitCode();
+#endif
+
        return ::system(command.c_str());
 }