/usr/include/net-snmp/library/ is in libsnmp-dev 5.4.3~dfsg-2.4ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/net-snmp/library/README
/usr/include/net-snmp/library/asn1.h
/usr/include/net-snmp/library/callback.h
/usr/include/net-snmp/library/check_varbind.h
/usr/include/net-snmp/library/cmu_compat.h
/usr/include/net-snmp/library/container.h
/usr/include/net-snmp/library/container_binary_array.h
/usr/include/net-snmp/library/container_iterator.h
/usr/include/net-snmp/library/container_list_ssll.h
/usr/include/net-snmp/library/container_null.h
/usr/include/net-snmp/library/data_list.h
/usr/include/net-snmp/library/default_store.h
/usr/include/net-snmp/library/factory.h
/usr/include/net-snmp/library/fd_event_manager.h
/usr/include/net-snmp/library/file_utils.h
/usr/include/net-snmp/library/getopt.h
/usr/include/net-snmp/library/int64.h
/usr/include/net-snmp/library/keytools.h
/usr/include/net-snmp/library/lcd_time.h
/usr/include/net-snmp/library/md5.h
/usr/include/net-snmp/library/mib.h
/usr/include/net-snmp/library/mibincl.h
/usr/include/net-snmp/library/mt_support.h
/usr/include/net-snmp/library/oid_stash.h
/usr/include/net-snmp/library/parse.h
/usr/include/net-snmp/library/read_config.h
/usr/include/net-snmp/library/scapi.h
/usr/include/net-snmp/library/snmp-tc.h
/usr/include/net-snmp/library/snmp.h
/usr/include/net-snmp/library/snmpCallbackDomain.h
/usr/include/net-snmp/library/snmpTCPDomain.h
/usr/include/net-snmp/library/snmpTCPIPv6Domain.h
/usr/include/net-snmp/library/snmpUDPDomain.h
/usr/include/net-snmp/library/snmpUDPIPv6Domain.h
/usr/include/net-snmp/library/snmpUnixDomain.h
/usr/include/net-snmp/library/snmp_alarm.h
/usr/include/net-snmp/library/snmp_api.h
/usr/include/net-snmp/library/snmp_assert.h
/usr/include/net-snmp/library/snmp_client.h
/usr/include/net-snmp/library/snmp_debug.h
/usr/include/net-snmp/library/snmp_enum.h
/usr/include/net-snmp/library/snmp_impl.h
/usr/include/net-snmp/library/snmp_logging.h
/usr/include/net-snmp/library/snmp_parse_args.h
/usr/include/net-snmp/library/snmp_secmod.h
/usr/include/net-snmp/library/snmp_service.h
/usr/include/net-snmp/library/snmp_transport.h
/usr/include/net-snmp/library/snmpusm.h
/usr/include/net-snmp/library/snmpv3-security-includes.h
/usr/include/net-snmp/library/snmpv3.h
/usr/include/net-snmp/library/system.h
/usr/include/net-snmp/library/text_utils.h
/usr/include/net-snmp/library/tools.h
/usr/include/net-snmp/library/transform_oids.h
/usr/include/net-snmp/library/ucd_compat.h
/usr/include/net-snmp/library/vacm.h
/usr/include/net-snmp/library/winpipe.h
/usr/include/net-snmp/library/winservice.h