/usr/include/ is in libsigc++-1.2-dev 1.2.7-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/sigc++-1.2/
/usr/include/sigc++-1.2/sigc++/
/usr/include/sigc++-1.2/sigc++/bind_return.h
/usr/include/sigc++-1.2/sigc++/object_slot.h
/usr/include/sigc++-1.2/sigc++/retype_return.h
/usr/include/sigc++-1.2/sigc++/slot.h
/usr/include/sigc++-1.2/sigc++/bind.h
/usr/include/sigc++-1.2/sigc++/class_slot.h
/usr/include/sigc++-1.2/sigc++/hide.h
/usr/include/sigc++-1.2/sigc++/retype.h
/usr/include/sigc++-1.2/sigc++/signal.h
/usr/include/sigc++-1.2/sigc++/method_slot.h
/usr/include/sigc++-1.2/sigc++/adaptor.h
/usr/include/sigc++-1.2/sigc++/connection.h
/usr/include/sigc++-1.2/sigc++/marshal.h
/usr/include/sigc++-1.2/sigc++/node.h
/usr/include/sigc++-1.2/sigc++/object.h
/usr/include/sigc++-1.2/sigc++/sigc++.h
/usr/include/sigc++-1.2/sigc++/trait.h
/usr/include/sigc++-1.2/sigc++/macros/
/usr/include/sigc++-1.2/sigc++/macros/bind_return.h.m4
/usr/include/sigc++-1.2/sigc++/macros/method_slot.h.m4
/usr/include/sigc++-1.2/sigc++/macros/object_slot.h.m4
/usr/include/sigc++-1.2/sigc++/macros/retype_return.h.m4
/usr/include/sigc++-1.2/sigc++/macros/slot.h.m4
/usr/include/sigc++-1.2/sigc++/macros/bind.h.m4
/usr/include/sigc++-1.2/sigc++/macros/class_slot.h.m4
/usr/include/sigc++-1.2/sigc++/macros/hide.h.m4
/usr/include/sigc++-1.2/sigc++/macros/retype.h.m4
/usr/include/sigc++-1.2/sigc++/macros/signal.h.m4
/usr/include/sigc++-1.2/sigc++/macros/template.macros.m4