systems don't copy all properties of listening socket to the new socket.

+ Fixed clients printf/usage bugs (ITS#749)
+ Fixed slapd spasswd support (ITS#751)
+ Fixed --enable-spasswd (ITS#751)
+ Fixed ldif(5) file:/// bug (ITS#750)

Update SASL Support

fix compiler warnings by including ac/unistd.h and only declaring copy_hostent() when we actually need to use it

s/LDAP_PF_UNIX/LDAP_PF_LOCAL/ so that we actually declare ldap_connect_to_path(). Also fix the decleration to match the function