ProjectExplorer: export NodesVisitor

and deinline dtor. It saves 2 copies

cd /io/qt/qt-creator-build/lib/qtcreator/plugins &&
nm -C ./*.so | grep vtable | grep -v " U " | cut -c 18- | sort | uniq -c
| grep -v " 1 "

      3 d vtable for ProjectExplorer::NodesVisitor
      5 d vtable for QFutureInterface<bool>
      2 d vtable for QFutureInterface<Core::LocatorFilterEntry>
      2 d vtable for QFutureInterface<TextEditor::HighlightingResult>
     18 d vtable for QFutureInterface<void>
      2 d vtable for QFutureWatcher<TextEditor::HighlightingResult>
      5 d vtable for QFutureWatcher<void>
      2 d vtable for QmlDesigner::(anonymous namespace)::TreeViewStyle
     14 d vtable for QRunnable
      3 d vtable for QtConcurrent::RunFunctionTaskBase<void>
      3 d vtable for QtConcurrent::RunFunctionTask<void>
      2 d vtable for RemoteLinux::Internal::(anonymous
namespace)::ConfigWidget
      2 d vtable for Utils::View<QListView>
     11 d vtable for Utils::View<QTreeView>
      2 V vtable for Core::BaseFileFilter::Iterator
      3 V vtable for CPlusPlus::SymbolVisitor
      3 V vtable for CppTools::CppRefactoringChanges
      5 V vtable for ProjectExplorer::BuildInfo
      3 V vtable for ProjectExplorer::JsonWizardPageFactory
      2 V vtable for QmlJS::SimpleAbstractStreamReader
      2 V vtable for QmlJSTools::QmlJSRefactoringChanges
      8 V vtable for VcsBase::VcsBaseOptionsPage

similar to QTBUG-45582

Change-Id: I75f7f5cf5522d1d093b52f4f0ee8cccdbca45cae
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>

src/plugins/projectexplorer/nodesvisitor.cpp

@@ -128,3 +128,7 @@ void FindAllFilesVisitor::visitFolderNode(FolderNode *folderNode)
     foreach (const FileNode *fileNode, folderNode->fileNodes())
         m_filePaths.append(fileNode->path());
 }
+
+NodesVisitor::~NodesVisitor()
+{
+}

src/plugins/projectexplorer/nodesvisitor.h

@@ -45,9 +45,9 @@ class SessionNode;
 class ProjectNode;
 class FolderNode;
 
-class NodesVisitor {
+class PROJECTEXPLORER_EXPORT NodesVisitor {
 public:
-    virtual ~NodesVisitor() {}
+    virtual ~NodesVisitor();
 
     virtual void visitSessionNode(SessionNode *) {}
     virtual void visitProjectNode(ProjectNode *) {}