Algorithm: Make transform work with simple iterators

Do not require containers to provide a size() method. This
makes for a less optimized insertion into the target container,
but most Qt classes should still handle this ok.

The upside is that e.g. the treemodel iterators can now be
transformed.

Change-Id: I4f149720631d9efb7b787332f039074b4c796965
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/libs/utils/algorithm.h

@@ -263,7 +263,6 @@ struct TransformImpl {
     static C call(const SC &container, F function)
     {
         C result;
-        result.reserve(container.size());
         std::transform(container.begin(), container.end(),
                        inserter(result),
                        function);