Compilation warnings

Due to
```
Commit: 1a56a39b4a97452a5c7c2d8e9d39ab28ca33dff0 [1a56a39]
Commit Date: Friday, February 21, 2020 9:07:13 PM

Restructure section handling
```
a number of compilation warnings (Windows) appeared:
```
c:\projects\doxygen\src\section.h(51): warning C4099: 'SectionInfo': type name first seen using 'struct' now seen using 'class' [C:\projects\doxygen\build\src\_doxygen.vcxproj]
  c:\projects\doxygen\src\section.h(50): note: see declaration of 'SectionInfo'
```

1 files changed, 0 insertions, 1 deletions

diff --git a/src/outputlist.h b/src/outputlist.h
index 06c9185..a944e5c 100644
--- a/src/outputlist.h
+++ b/src/outputlist.h
@@ -45,7 +45,6 @@ class DotClassGraph;
 class DotDirDeps;
 class DotInclDepGraph;
 class DotGfxHierarchyTable;
-class SectionDict;
 class DotGroupCollaboration;
 class DocRoot;