[LyX/master] Fix memory leak.

[Pavel Sanda]

commit b7af21ad7c0a9c26600584ed122772214d1da9ef
Author: Pavel Sanda <sanda at lyx.org>
Date:   Tue Feb 18 10:03:42 2020 +0100

    Fix memory leak.
    
    Spotted by Scott.
    https://www.mail-archive.com/lyx-devel@lists.lyx.org/msg210447.html
---
 src/frontends/qt/TocModel.cpp |    7 +++++++
 src/frontends/qt/TocModel.h   |    1 +
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/src/frontends/qt/TocModel.cpp b/src/frontends/qt/TocModel.cpp
index 1974422..16990b8 100644
--- a/src/frontends/qt/TocModel.cpp
+++ b/src/frontends/qt/TocModel.cpp
@@ -336,6 +336,13 @@ void TocModels::updateItem(QString const & type, DocIterator const & dit)
 	models_[type]->updateItem(dit);
 }
 
+TocModels::~TocModels(){
+	QHashIterator<QString, TocModel *> iter(models_);
+	while(iter.hasNext()) {
+		iter.next();
+		delete iter.value();
+	}
+}
 
 void TocModels::reset(BufferView const * bv)
 {
diff --git a/src/frontends/qt/TocModel.h b/src/frontends/qt/TocModel.h
index 8d33639..ad65cdc 100644
--- a/src/frontends/qt/TocModel.h
+++ b/src/frontends/qt/TocModel.h
@@ -113,6 +113,7 @@ class TocModels : public QObject
 public:
 	///
 	TocModels();
+	~TocModels();
 	///
 	void reset(BufferView const * bv);
 	///