/usr/include/x86_64-linux-gnu/ is in libqt5scintilla2-dev 2.9.3+dfsg-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/x86_64-linux-gnu/qt5/
/usr/include/x86_64-linux-gnu/qt5/Qsci/
/usr/include/x86_64-linux-gnu/qt5/Qsci/qsciabstractapis.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qsciapis.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscicommand.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscicommandset.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscidocument.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qsciglobal.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexer.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexeravs.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerbash.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerbatch.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexercmake.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexercoffeescript.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexercpp.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexercsharp.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexercss.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexercustom.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerd.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerdiff.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerfortran.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerfortran77.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerhtml.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexeridl.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerjava.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerjavascript.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerlua.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexermakefile.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexermatlab.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexeroctave.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerpascal.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerperl.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerpo.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerpostscript.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerpov.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerproperties.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerpython.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerruby.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerspice.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexersql.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexertcl.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexertex.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerverilog.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexervhdl.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexerxml.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscilexeryaml.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscimacro.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qsciprinter.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qsciscintilla.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qsciscintillabase.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscistyle.h
/usr/include/x86_64-linux-gnu/qt5/Qsci/qscistyledtext.h