doxygen: exclude licensing blurbs

indra/llplugin/llpluginclassmedia.cpp

indra/llplugin/llpluginclassmedia.h

indra/llplugin/llpluginclassmediaowner.h

indra/llplugin/llplugininstance.cpp

indra/llplugin/llplugininstance.h

indra/llplugin/llpluginmessage.cpp

indra/llplugin/llpluginmessage.h

indra/llplugin/llpluginmessageclasses.h

indra/llplugin/llpluginmessagepipe.cpp

indra/llplugin/llpluginmessagepipe.h

indra/llplugin/llpluginprocesschild.cpp

indra/llplugin/llpluginprocesschild.h

indra/llplugin/llpluginprocessparent.cpp

indra/llplugin/llpluginprocessparent.h

indra/llplugin/llpluginsharedmemory.cpp

indra/llplugin/llpluginsharedmemory.h

indra/llplugin/slplugin/slplugin.cpp

indra/media_plugins/base/media_plugin_base.cpp

indra/media_plugins/base/media_plugin_base.h

indra/media_plugins/example/media_plugin_example.cpp