Do not send errors (other than referral) from ldif_back_referrals().
Return LDAP result code from ldif_back_entry_get().

Fix rev 1.91 patch: Reset ltp_pending_count when flushing ltp_pending_list.
Remove flush_pending_list() again and the now-unnecessary 2nd call to it.
Help the compiler a little.
Move ltp_work_list in case it makes a difference for caching.
Move mutex unlock in pool_destroy() to make concurrency debuggers happier.

Negate ltp_open_count when paused, avoids an ltp_pause test in pool_submit().

Replace ltp_state with ltp_finishing.  Drop state
LDAP_INT_THREAD_POOL_STOPPING, flush pending list instead.
ltp_max_pending = default value instead of 0, and negative when finishing.

Use ldap_pvt_thread_pool_pausing(): pause check for slapd without locking.

Add ldap_pvt_thread_pool_pausing(): pause check for slapd without locking.

Add ldap_pvt_thread_pool_pausing(): pause check for slapd without locking.
Make counters int instead of long; INT_MAX pending tasks is enough.
Nitpick cleanup: goto failure instead of if() to not-failure in _submit().

backends already do it.