Fix: Make sure umask is used when creating new files

When a new file was created from the file menu, the permissions
on *nix was always 0600 regardless of the proess' current umask.
Fixed by letting CorePlugin::initialize() initialize the umask in
Utils::SaveFile. Since getting the system's umask is not thread
safe this can't be done directly in SaveFile::open.

Task-number: QTCREATORBUG-6513
Change-Id: I10d8b2f4ab85574ed3004b5e646664c2255196b9
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/coreplugin/coreplugin.cpp

@@ -40,6 +40,7 @@
 #include "infobar.h"
 
 #include <extensionsystem/pluginmanager.h>
+#include <utils/savefile.h>
 
 #include <QtPlugin>
 #include <QDebug>
@@ -95,6 +96,10 @@ bool CorePlugin::initialize(const QStringList &arguments, QString *errorMessage)
         m_designMode = new DesignMode;
         InfoBar::initializeGloballySuppressed();
     }
+
+    // Make sure we respect the process's umask when creating new files
+    Utils::SaveFile::initializeUmask();
+
     return success;
 }