/usr/include/android-21/cutils/ is in android-headers-21 23-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/android-21/cutils/android_reboot.h
/usr/include/android-21/cutils/aref.h
/usr/include/android-21/cutils/ashmem.h
/usr/include/android-21/cutils/atomic-arm.h
/usr/include/android-21/cutils/atomic-arm64.h
/usr/include/android-21/cutils/atomic-inline.h
/usr/include/android-21/cutils/atomic-mips.h
/usr/include/android-21/cutils/atomic-mips64.h
/usr/include/android-21/cutils/atomic-x86.h
/usr/include/android-21/cutils/atomic-x86_64.h
/usr/include/android-21/cutils/atomic.h
/usr/include/android-21/cutils/bitops.h
/usr/include/android-21/cutils/compiler.h
/usr/include/android-21/cutils/config_utils.h
/usr/include/android-21/cutils/cpu_info.h
/usr/include/android-21/cutils/debugger.h
/usr/include/android-21/cutils/dir_hash.h
/usr/include/android-21/cutils/fs.h
/usr/include/android-21/cutils/hashmap.h
/usr/include/android-21/cutils/iosched_policy.h
/usr/include/android-21/cutils/jstring.h
/usr/include/android-21/cutils/klog.h
/usr/include/android-21/cutils/list.h
/usr/include/android-21/cutils/log.h
/usr/include/android-21/cutils/memory.h
/usr/include/android-21/cutils/misc.h
/usr/include/android-21/cutils/multiuser.h
/usr/include/android-21/cutils/native_handle.h
/usr/include/android-21/cutils/open_memstream.h
/usr/include/android-21/cutils/partition_utils.h
/usr/include/android-21/cutils/process_name.h
/usr/include/android-21/cutils/properties.h
/usr/include/android-21/cutils/qtaguid.h
/usr/include/android-21/cutils/record_stream.h
/usr/include/android-21/cutils/sched_policy.h
/usr/include/android-21/cutils/sockets.h
/usr/include/android-21/cutils/str_parms.h
/usr/include/android-21/cutils/threads.h
/usr/include/android-21/cutils/trace.h
/usr/include/android-21/cutils/uevent.h