/usr/include/atomic_ops/sysdeps/gcc/ is in libatomic-ops-dev 7.2~alpha5+cvs20101124-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/atomic_ops/sysdeps/gcc/alpha.h
/usr/include/atomic_ops/sysdeps/gcc/arm.h
/usr/include/atomic_ops/sysdeps/gcc/avr32.h
/usr/include/atomic_ops/sysdeps/gcc/cris.h
/usr/include/atomic_ops/sysdeps/gcc/hppa.h
/usr/include/atomic_ops/sysdeps/gcc/ia64.h
/usr/include/atomic_ops/sysdeps/gcc/m68k.h
/usr/include/atomic_ops/sysdeps/gcc/mips.h
/usr/include/atomic_ops/sysdeps/gcc/powerpc.h
/usr/include/atomic_ops/sysdeps/gcc/s390.h
/usr/include/atomic_ops/sysdeps/gcc/sh.h
/usr/include/atomic_ops/sysdeps/gcc/sparc.h
/usr/include/atomic_ops/sysdeps/gcc/x86.h
/usr/include/atomic_ops/sysdeps/gcc/x86_64.h