/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/ is in gcc-4.8-plugin-dev 4.8.5-4ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/att.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/biarch64.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/gnu-user-common.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/gnu-user64.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/i386-opts.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/i386-protos.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/i386.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/linux-common.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/linux64.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/unix.h
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/i386/x86-64.h