Re: (ITS#6625) draft-zeilenga-ldap-c-api-concurrency support

[h.b.furuseth@usit.uio.no]

I've made two fixes (I hope) to the concurrency commit, please review:

- I inverted the test in NT threads MUTEX_FIRSTCREATE.  I assume
  LDO_MUTEX_NULL = (HANDLE)0 is not a valid handle, so FIRSTCREATE
  must initialize m if it *is* 0, not if is *not*.

- In do_abandon(), protected ldap_free_connection() with
  ld->ld_conn_mutex.  The function would unlock it when it did not own
  the mutex.

  However I do not know why the mutex was moved out of
  ldap_free_connection(), so maybe something more needs to be done.

Also I've cleaned up macros and namespace:

  Add proper values for NO_THREADS.  Support LDAP_THREAD_DEBUG.
  Define LDAP_INT_* and LDAP_DEBUG_* in ldap_int_thread.h,
  LDAP_PVT_* in ldap_pvt_thread.h.

  libraries/libldap/ldap-int.h:
    Remove unnecessary #ifdef LDAP_R_COMPILE for LDAP_NEXT_MSGID.

    define LDAP_LDO_MUTEX_NULLARG as ,LDAP_PVT_MUTEX_NULL or empty
    in the same place which decides whether the initializer is needed.
  
  Wrap some macros and arguments in parens or do{}while(0), so they
  can be used more like C statements.  Also replace empty macros with
  ((void) 0) expansions, to shut up 'empty statement' compiler warnings.

Finally, I've another wish for the test060-mt-hot:

  This test takes way to long under Valgrind.  It ought to obey
  $TESTLOOPS (default 50) like the concurrency tests do:  Set
  parameters to run ca $TESTLOOPS/50 of the current time.

  I don't know which parameters it's best to reduce in that case,
  however?

-- 
Hallvard