/usr/include/php/20170718/ext/hash/ is in php7.2-dev 7.2.3-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/php/20170718/ext/hash/php_hash.h
/usr/include/php/20170718/ext/hash/php_hash_adler32.h
/usr/include/php/20170718/ext/hash/php_hash_crc32.h
/usr/include/php/20170718/ext/hash/php_hash_fnv.h
/usr/include/php/20170718/ext/hash/php_hash_gost.h
/usr/include/php/20170718/ext/hash/php_hash_haval.h
/usr/include/php/20170718/ext/hash/php_hash_joaat.h
/usr/include/php/20170718/ext/hash/php_hash_md.h
/usr/include/php/20170718/ext/hash/php_hash_ripemd.h
/usr/include/php/20170718/ext/hash/php_hash_sha.h
/usr/include/php/20170718/ext/hash/php_hash_sha3.h
/usr/include/php/20170718/ext/hash/php_hash_snefru.h
/usr/include/php/20170718/ext/hash/php_hash_tiger.h
/usr/include/php/20170718/ext/hash/php_hash_whirlpool.h