Use AC_CHECK_TYPE(S) instead of old macros

The diff between 1.586.2.1 and 1.586.2.2 need to be carefully examined.

add authzSyntax for authzTo/authzFrom attributes; add X-ORDERED 'VALUES' if support for ordered_value_{validate,pretty,normalize} is present; exploit normalization in slap_parseURI (only #ifdef LDAP_DEVEL)

solve a deadlock during unbind: ldap_send_unbind() is called by ldap_free_connection() only, and just in case the last arg is not 0; but most of the times ldap_free_connection() is called with ld_req_mutex locked, so it shouldn't be locked again from inside ldap_send_unbind()

configure.in and build/*.m4 have to be updated first to latest autoconf (ugh)

aclocal.m4 not fully updated.  Could be a problem???