LGTM: Move seq->next out of loop control

LGTM points out that the construct use in the loop here "does
nothing" -- that is, it is a conditional whose result is never used.
It is apparently being used simply to ensure that the next() function is
called on each loop iteration, but because sequence may be null, it is
shoehorned into a trinary :? operator. To clarify the intent and ensure
that later readers (including LGTM) do not misunderstand it,
this code is broken out into a more standard conditional construct at
the end of each loop iteration.

src/App/Document.cpp

@@ -3484,7 +3484,7 @@ int Document::recompute(const std::vector<App::DocumentObject*> &objs, bool forc
             if(canAbort)
                 seq.reset(new Base::SequencerLauncher("Recompute...", topoSortedObjects.size()));
             FC_LOG("Recompute pass " << passes);
-            for (;idx<topoSortedObjects.size();(seq?seq->next(true):true),++idx) {
+            for (; idx < topoSortedObjects.size(); ++idx) {
                 auto obj = topoSortedObjects[idx];
                 if(!obj->getNameInDocument() || filter.find(obj)!=filter.end())
                     continue;
@@ -3515,6 +3515,8 @@ int Document::recompute(const std::vector<App::DocumentObject*> &objs, bool forc
                     for (auto inObjIt : obj->getInList())
                         inObjIt->enforceRecompute();
                 }
+                if (seq)
+                    seq->next(true);
             }
             // check if all objects are recomputed but still thouched
             for (size_t i=0;i<topoSortedObjects.size();++i) {