Add an Attribute declared but not referenced script

[jjhursey]

• Adds a script to list all of the attributes that have been declared
  but have no reference in the document outside of the declaration.
• Fixes a typo in the internal cross referencing
• Add a new make target make check that runs this additional check
  and displays the list of attributes missing a reference.
• Ref Issue Many attributes presented in request-related attributes sectiion have no clear use #185

[jjhursey]

This is probably useful to have in the v3 standard as an option as well.

Here is the report out for the v3 branch:

$$ make check
====> Checking for Attributes Declared, but not referenced
Attribute Missing Reference: PMIX_ATTR_UNDEF
Attribute Missing Reference: PMIX_RECONNECT_SERVER
Attribute Missing Reference: PMIX_TOPOLOGY_FILE
Attribute Missing Reference: PMIX_LOCALITY_STRING
Attribute Missing Reference: PMIX_PROC_BLOB
Attribute Missing Reference: PMIX_ARCH
Attribute Missing Reference: PMIX_DEBUG_APP_DIRECTIVES
Attribute Missing Reference: PMIX_SERVER_ENABLE_MONITORING
Attribute Missing Reference: PMIX_DEBUG_STOP_ON_EXEC
Attribute Missing Reference: PMIX_RM_VERSION
Attribute Missing Reference: PMIX_NOTIFY_COMPLETION
Attribute Missing Reference: PMIX_IOF_COMPLETE
Attribute Missing Reference: PMIX_CLIENT_AVG_MEMORY
Attribute Missing Reference: PMIX_EVENT_TEXT_MESSAGE
Attribute Missing Reference: PMIX_SEND_HEARTBEAT
Attribute Missing Reference: PMIX_HWLOC_SHARE_TOPO
Attribute Missing Reference: PMIX_CREDENTIAL
Attribute Missing Reference: PMIX_SET_ENVAR
Attribute Missing Reference: PMIX_HWLOC_SHMEM_FILE
Attribute Missing Reference: PMIX_THREADING_MODEL
Attribute Missing Reference: PMIX_DAEMON_MEMORY
Attribute Missing Reference: PMIX_UNSET_ENVAR
Attribute Missing Reference: PMIX_TOPOLOGY
Attribute Missing Reference: PMIX_NET_TOPO
Attribute Missing Reference: PMIX_CRYPTO_KEY
Attribute Missing Reference: PMIX_EXIT_CODE
Attribute Missing Reference: PMIX_MODEL_NUM_CPUS
Attribute Missing Reference: PMIX_APPEND_ENVAR
Attribute Missing Reference: PMIX_VERSION_INFO
Attribute Missing Reference: PMIX_APP_MAP_REGEX
Attribute Missing Reference: PMIX_MODEL_AFFINITY_POLICY
Attribute Missing Reference: PMIX_CPUSET
Attribute Missing Reference: PMIX_PROC_PID
Attribute Missing Reference: PMIX_EVENT_PROXY
Attribute Missing Reference: PMIX_RM_NAME
Attribute Missing Reference: PMIX_HWLOC_HOLE_KIND
Attribute Missing Reference: PMIX_ADD_ENVAR
Attribute Missing Reference: PMIX_TDIR_RMCLEAN
Attribute Missing Reference: PMIX_DEBUG_WAIT_FOR_NOTIFY
Attribute Missing Reference: PMIX_ANL_MAP
Attribute Missing Reference: PMIX_TOPOLOGY_SIGNATURE
Attribute Missing Reference: PMIX_HWLOC_SHMEM_SIZE
Attribute Missing Reference: PMIX_MAP_BLOB
Attribute Missing Reference: PMIX_EVENT_NO_TERMINATION
Attribute Missing Reference: PMIX_SERVER_HOSTNAME
Attribute Missing Reference: PMIX_DEBUG_STOP_IN_INIT
Attribute Missing Reference: PMIX_LOCAL_TOPO
Attribute Missing Reference: PMIX_MODEL_NUM_THREADS
Attribute Missing Reference: PMIX_SPAWN_TOOL
Attribute Missing Reference: PMIX_LOG_EMAIL_SERVER
Attribute Missing Reference: PMIX_PROGRAMMING_MODEL
Attribute Missing Reference: PMIX_PROCDIR
Attribute Missing Reference: PMIX_CLUSTER_ID
Attribute Missing Reference: PMIX_LAUNCHER
Attribute Missing Reference: PMIX_EVENT_DO_NOT_CACHE
Attribute Missing Reference: PMIX_MODEL_LIBRARY_NAME
Attribute Missing Reference: PMIX_DEBUG_JOB_DIRECTIVES
Attribute Missing Reference: PMIX_COSPAWN_APP
Attribute Missing Reference: PMIX_PREPEND_ENVAR
Attribute Missing Reference: PMIX_MODEL_PHASE_TYPE
Attribute Missing Reference: PMIX_MODEL_LIBRARY_VERSION
Attribute Missing Reference: PMIX_EVENT_WANT_TERMINATION
Attribute Missing Reference: PMIX_DSTPATH
Attribute Missing Reference: PMIX_SERVER_GATEWAY
Attribute Missing Reference: PMIX_LOCALITY
Attribute Missing Reference: PMIX_LOG_EMAIL_SENDER_ADDR
Attribute Missing Reference: PMIX_MODEL_CPU_TYPE
Attribute Missing Reference: PMIX_QUERY_AUTHORIZATIONS
Attribute Missing Reference: PMIX_MODEL_PHASE_NAME
Attribute Missing Reference: PMIX_JOB_TERM_STATUS
Attribute Missing Reference: PMIX_DEBUG_JOB
Attribute Missing Reference: PMIX_NODE_LIST
Attribute Missing Reference: PMIX_HWLOC_SHMEM_ADDR
Attribute Missing Reference: PMIX_PROC_STATE_STATUS
Attribute Missing Reference: PMIX_APP_MAP_TYPE
Attribute Missing Reference: PMIX_DEBUG_WAITING_FOR_NOTIFY
Attribute Missing Reference: PMIX_LOG_EMAIL_SRVR_PORT
Attribute Missing Reference: PMIX_TOPOLOGY_XML
 78 of 325 Attributes are missing reference
make: *** [check] Error 78

[jjhursey]

Cherry Pick of PR #223

[jjhursey]

@rhc54 can you give this a 👍 and merge for the v3.x branch? That way we have the script over there too if we need it.