Make it possible to use non-autodetected Qt for Symbian.

Users can specify a S60 SDK root for Qt for Symbian versions
now.

src/plugins/qt4projectmanager/qt-s60/s60devices.cpp

@@ -214,6 +214,16 @@ S60Devices::Device S60Devices::deviceForId(const QString &id) const
     return Device();
 }
 
+S60Devices::Device S60Devices::deviceForEpocRoot(const QString &root) const
+{
+    foreach (const S60Devices::Device &i, m_devices) {
+        if (i.epocRoot == root) {
+            return i;
+        }
+    }
+    return Device();
+}
+
 QString S60Devices::cleanedRootPath(const QString &deviceRoot)
 {
     QString path = deviceRoot;