Fix UBSan build's RTTI needs

...after 3ba92b5f1eaf7d4447a0943ea260db515ca799dc "hide more symbols" had caused
CppunitTest_desktop_lib to fail with

> DynamicLibraryManagerException: "Failed to load dynamic library: workdir/LinkTarget/CppunitTest/libtest_desktop_lib.so
> workdir/LinkTarget/CppunitTest/libtest_desktop_lib.so: undefined symbol: _ZTIN7desktop20CallbackFlushHandlerE"

Change-Id: I051e1a233757a6ccb7cf9ea564ab6b510d6df571
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/163742
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <stephan.bergmann@allotropia.de>
diff --git a/desktop/inc/lib/init.hxx b/desktop/inc/lib/init.hxx
index f6ff4be..614ef40 100644
--- a/desktop/inc/lib/init.hxx
+++ b/desktop/inc/lib/init.hxx
@@ -93,7 +93,7 @@ namespace desktop {
    };

    /// One instance of this per view, handles flushing callbacks
    class CallbackFlushHandler final : public Idle, public SfxLokCallbackInterface
    class SAL_DLLPUBLIC_RTTI CallbackFlushHandler final : public Idle, public SfxLokCallbackInterface
    {
    public:
        DESKTOP_DLLPUBLIC explicit CallbackFlushHandler(LibreOfficeKitDocument* pDocument, LibreOfficeKitCallback pCallback, void* pData);