/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/ is in gcc-8-plugin-dev-mips64-linux-gnuabi64 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/dbxelf.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/elfos.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/glibc-stdint.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/gnu-user.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/initfini-array.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/linux-android.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/linux-protos.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/linux.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/gnu-user.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/linux-common.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/linux.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/mips-opts.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/mips-protos.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/mips/mips.h
/usr/lib/gcc-cross/mips64-linux-gnuabi64/8/plugin/include/config/vxworks-dummy.h