Symbian/Linux: Enable building with makefile-based system.

- Autodetect SDK by environment variable EPOCROOT and qt directory
below.
- Environment::appendOrSet/prependOrSet: Avoid duplicate entries
- Rename toolchain enumeration value
- Adapt S60ToolChainMixin to new GnuPoc setup, provide routines for
  all required variables.
- RVCTToolChain: Make RVCT detection smarter (Check for RVCT<v1><v2>BIN
  variable). Set all required variables in case of RVCTToolChain/GnuPoc
- QtVersionManager: Detect toolchain and Qt version properly, make S60
  device run config accept toolchain.
- Modify S60DeviceRunControl to execute 'make sis'
- Modify S60Devices::detectQt...() to check for Qt installed into SDK
  first and symlink as fallback.

src/plugins/qt4projectmanager/qt-s60/s60devicespreferencepane.cpp

@@ -32,8 +32,10 @@
 
 #include <qt4projectmanager/qt4projectmanagerconstants.h>
 
+#include <utils/qtcassert.h>
+
 #include <QtCore/QDir>
-#include <QtDebug>
+#include <QtCore/QtDebug>
 
 using namespace Qt4ProjectManager;
 using namespace Qt4ProjectManager::Internal;
@@ -56,7 +58,7 @@ S60DevicesWidget::~S60DevicesWidget()
 void S60DevicesWidget::updateDevices()
 {
     m_devices->read();
-    Q_ASSERT(m_devices->detectQtForDevices());
+    QTC_ASSERT(m_devices->detectQtForDevices(), return);
     updateDevicesList();
 }