Make Utils::transform more generic

- Works for all container types now, defaulting to
  the same container type for input and output

- Enables specifying the result container type,
  e.g. QSet<X> x = Utils::transform<QSet>(list, function);

- Use our own inserter instead of std::back_inserter,
  to enable usage with QSet<>

Change-Id: I7256e51430bfc1409456c68b6ee270778b95e9d5
Reviewed-by: hjk <hjk121@nokiamail.com>

src/libs/utils/codegeneration.cpp

@@ -110,8 +110,8 @@ void writeQtIncludeSection(const QStringList &qt4,
     else
         trans = [](const QString &i) { return i.mid(i.indexOf(QLatin1Char('/')) + 1); };
 
-    QSet<QString> qt4Only = QSet<QString>::fromList(Utils::transform(qt4, trans));
-    QSet<QString> qt5Only = QSet<QString>::fromList(Utils::transform(qt5, trans));
+    QSet<QString> qt4Only = Utils::transform<QSet>(qt4, trans);
+    QSet<QString> qt5Only = Utils::transform<QSet>(qt5, trans);
 
     if (addQtVersionCheck) {
         QSet<QString> common = qt4Only;