Clean up headers.

This should be tunable...

macros into our namespace and limit use to headers.  A subsequent
round will add macros to separately handle forward declarations
of variables from declaration of function prototypes.  The last
round will add additional macros for declaring actual variables and
functions.

r/w locks and thread pools.  Hide internal structures (using
pthread'ish technics).  Place common code in threads.c.  Move
no-thread code to thr_stub.c.  Move thread pool code to tpool.c.
Removed setconcurrency call from initializer, added 'concurrency'
directive to slapd.  Tested code under pthreads, pth, and no-threads.

#define PTH_SYSCALL_SOFT 1

Update single debug/release not to use service manager nor event manager.
Likely breaks MINGW32 port.

ifdefs to depend on _WINNT, which is bogus. Added _WIN32 back on these ifs,
and fixed some other include problems.

See README 1.27 log

Tests behave as expected excepting slapd sometimes does not
shutdown properly.

This commit includes many changes.  All changes compile under NT but
have not been tested under UNIX.

A Summary of changes (likely incomplete):

NT changes:
	Removed lint.
	Clean up configuration support for "Debug", "Release", "SDebug",
		and "SRelease" configurations.
	Share output directories for clients, libraries,
		and slapd.  (maybe they should be combined further
		and moved to build/{,S}{Debug,Release}).
	Enable threading when _MT is defined.
	Enable debuging when _DEBUG is defined.
	Disable setting of NDEBUG under Release/SRelease.  Asserts
		are disabled in <ac/assert.h> when LDAP_DEBUG is not
		defined.
	Added 'build/main.dsp' Master project.
	Removed non-slapd projects from slapd.dsp (see main.dsp).
	Removed replaced many uses of _WIN32 macro with feature based
		macros.

ldap_cdefs.h changes
	#define LDAP_CONST const
		(see below)
	#define LDAP_F(type) LDAP_F_PRE type LDAP_F_POST
		To allow specifiers to be added before and after
		the type declaration.  (For DLL handling)

LBER/LDAP changes
	Namespace changes:
		s/lber_/ber_/ for here and there.
		s/NAME_ERROR/LDAP_NAME_ERROR/g
	Deleted NULLMSG and other NULL* macros for namespace reasons.
	"const" libraries.  Installed headers (ie: lber.h, ldap.h)
		use LDAP_CONST macro.  Normally set to 'const' when
		__STDC__.  Can be set externally to enable/disable
		'constification' of external interface.  Internal
		interface always uses 'const'.  Did not fix warnings
		in -lldif (in lieu of new LDIF parser).

	Added _ext API implementations (excepting search and bind).
		Need to implement ldap_int_get_controls() for reponses
		with controls.

	Added numberous assert() checks.

LDAP_R
	_MT defines HAVE_NT_THREADS
	Added numberous assert() checks.
	Changed ldap_pthread_t back to unsigned long.  Used cast
	to HANDLE in _join().

LDBM
	Replaced _WIN32 with HAVE_SYSLOG

ud
	Added version string if MKVERSION is not defined.  (MKVERSION
		needs to be set under UNIX).

slapd
	Made connection sockbuf field a pointer to a sockbuf.  This
		removed slap.h dependency on lber-int.h.  lber-int.h now only
		included by those files needing to mess with the sockbuf.
	Used ber_* functions/macros to access sockbuf internals whenever
		possible.
	Added version string if MKVERSION is not defined.  (MKVERSION
		needs to be set under UNIX).
	Removed FD_SET unsigned lint

slapd/tools
	Used EXEEXT to added ".exe" to routines.  Need to define EXEEXT
		under UNIX.

ldappasswd
	Added ldappasswd.dsp.  Ported to NT.  Used getpid() to seed rand().

nt_debug
	Minor cleanup.  Added "portable.h" include and used <ac/*.h> where
	appropriate.  Added const to char* format argument.

Move all SunOS routines (ie: _sleep() and its helpers) to thr_lwp.c
so that it's internals can be 'static'.  Add 'static' to thr_lwp.c.
Add comment to LWP:  NEEDS WORK, may not compile!  Need some
SunOS user to sort out the details.  Volunteers?

okay to read and write LDBM specific fields (state, refcnt,
LRU.  The id field, though is read-only once set.
cache_find_entry_dn2id(), hence, does not require any entry locks.
cache_find_entry_id() must do a entry_rdwr_trylock() and back
off if busy.
Add new rdwr lock code with trylock() functionality.
Implement entry_rdwr_trylock().

	Likely broke things for non-posix threadings....

Update -lldap_r implementation to:
	remove attribute support
	hide thread detachment
	provide concurrency accessors
	provide initialization function
	fix gethostby{addr,name}_r codes (not coverred by HAVE_REENTRANT_FUNCTIONS)
Update servers/libraries to use ldap_pvt_thread_ calls.
Cleanup server codes (no #ifdef HAVE_PTHREAD_THIS or _THATs)!
Removed -llthread

Assume portable.h has been included
Include ldap_cdefs.h at the top.

Updates for the new threading and utility stuff in libldap{_r}.