AC_SOCKET_INVALID nitpick: ((unsigned)~0) [needs 2's compl.] -> ((unsigned)-1)

be sent to transmit client credentials. Buffer the message data.

(with notable exceptions: ignore tests for EINTR which winsock never sets)

This does not happen normally.

internal atexit handler.

Clean up headers.

Calls to gai_strerror() should be replaced with calls AC_GAI_STRERROR().

s/LDAP_PF_UNIX/LDAP_PF_LOCAL/
s/AF_UNIX/AF_LOCAL/
s/PF_UNIX/PF_LOCAL/

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.