Bug 573573 - [GTK3] Tree.rendererRender() leaks native memory

This change adds a missing gtk_tree_path_free() in
Tree.rendererRender(), to avoid a native memory leak.

Change-Id: I6214b45045e490ec80ef1ae2367633bcf43a3d20
Signed-off-by: Simeon Andreev <simeon.danailov.andreev@gmail.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.swt/+/180664
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java
index 5bace6a..9fcfd32 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java
@@ -3365,6 +3365,7 @@
 					GTK.gtk_widget_realize (handle);
 					path = GTK.gtk_tree_model_get_path (modelHandle, iter);
 					GTK.gtk_tree_view_get_cell_area (handle, path, columnHandle, rect3);
+					GTK.gtk_tree_path_free (path);
 					contentX[0] += rect3.x;
 				}
 				GC gc = getGC(cr);