/usr/include/libmemcached-1.0/ is in libmemcached-dev 1.0.18-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libmemcached-1.0/alloc.h
/usr/include/libmemcached-1.0/allocators.h
/usr/include/libmemcached-1.0/analyze.h
/usr/include/libmemcached-1.0/auto.h
/usr/include/libmemcached-1.0/basic_string.h
/usr/include/libmemcached-1.0/behavior.h
/usr/include/libmemcached-1.0/callback.h
/usr/include/libmemcached-1.0/callbacks.h
/usr/include/libmemcached-1.0/configure.h
/usr/include/libmemcached-1.0/defaults.h
/usr/include/libmemcached-1.0/delete.h
/usr/include/libmemcached-1.0/deprecated_types.h
/usr/include/libmemcached-1.0/dump.h
/usr/include/libmemcached-1.0/encoding_key.h
/usr/include/libmemcached-1.0/error.h
/usr/include/libmemcached-1.0/exception.hpp
/usr/include/libmemcached-1.0/exist.h
/usr/include/libmemcached-1.0/fetch.h
/usr/include/libmemcached-1.0/flush.h
/usr/include/libmemcached-1.0/flush_buffers.h
/usr/include/libmemcached-1.0/get.h
/usr/include/libmemcached-1.0/hash.h
/usr/include/libmemcached-1.0/limits.h
/usr/include/libmemcached-1.0/memcached.h
/usr/include/libmemcached-1.0/memcached.hpp
/usr/include/libmemcached-1.0/options.h
/usr/include/libmemcached-1.0/parse.h
/usr/include/libmemcached-1.0/platform.h
/usr/include/libmemcached-1.0/quit.h
/usr/include/libmemcached-1.0/result.h
/usr/include/libmemcached-1.0/return.h
/usr/include/libmemcached-1.0/sasl.h
/usr/include/libmemcached-1.0/server.h
/usr/include/libmemcached-1.0/server_list.h
/usr/include/libmemcached-1.0/stats.h
/usr/include/libmemcached-1.0/storage.h
/usr/include/libmemcached-1.0/strerror.h
/usr/include/libmemcached-1.0/struct/
/usr/include/libmemcached-1.0/struct/allocator.h
/usr/include/libmemcached-1.0/struct/analysis.h
/usr/include/libmemcached-1.0/struct/callback.h
/usr/include/libmemcached-1.0/struct/memcached.h
/usr/include/libmemcached-1.0/struct/result.h
/usr/include/libmemcached-1.0/struct/sasl.h
/usr/include/libmemcached-1.0/struct/server.h
/usr/include/libmemcached-1.0/struct/stat.h
/usr/include/libmemcached-1.0/struct/string.h
/usr/include/libmemcached-1.0/touch.h
/usr/include/libmemcached-1.0/triggers.h
/usr/include/libmemcached-1.0/types/
/usr/include/libmemcached-1.0/types.h
/usr/include/libmemcached-1.0/types/behavior.h
/usr/include/libmemcached-1.0/types/callback.h
/usr/include/libmemcached-1.0/types/connection.h
/usr/include/libmemcached-1.0/types/hash.h
/usr/include/libmemcached-1.0/types/return.h
/usr/include/libmemcached-1.0/types/server_distribution.h
/usr/include/libmemcached-1.0/verbosity.h
/usr/include/libmemcached-1.0/version.h
/usr/include/libmemcached-1.0/visibility.h