Added LDAP printer browsing support (STR #338)

Added LDAP printer browsing support (STR #338)

Browsing code cleanup.

config-scripts/cups-ldap.m4:
    - Added.

config.h.in:
    - Added HAVE_LDAP and HAVE_OPENLDAP definitions.

configure.in:
    - Include config-scripts/cups-ldap.m4.

scheduler/conf.c:
    - Added BrowseLDAPBindDN, BrowseLDAPDN, BrowseLDAPPassword,
      and BrowseLDAPServer configuration directives.
    - cupsdReadConfiguration(): Initialize new directives.

scheduler/dirsvc.c:
    - cupsdSendBrowseList(): Call cupsdSendLDAPBrowse() as
      needed.
    - cupsdSendLDAPBrowse(): Added.
    - cupsdSendSLPBrowse(): Add printer-type attribute to
      registration.
    - cupsdStartBrowsing(): Add LDAP initialization code.
    - cupsdStopBrowsing(): Add LDAP shutdown code.
    - cupsdUpdateCUPSBrowse(): Use new is_local_queue() function
      to detect local queues.
    - cupsdUpdateLDAPBrowse(): Added.
    - cupsdUpdateSLPBrowse(): Use new is_local_queue() function
      to detect local queues, and use printer type value from SLP
      attributes instead of guessing. Also free memory used by
      dummy printer entry.
    - is_local_queue(): Added.
    - process_browse_data(): Added host and resource arguments so
      that we don't do an extra httpSeparateURI() call.
    - slp_attr_callback(): Get printer type from printer-type
      attribute instead of building it from all of the others.

scheduler/dirsvc.h:
    - Include LDAP headers as needed.
    - Add LDAP browsing globals and prototypes.

scheduler/main.c:
    - main(): Call cupsdUpdateLDAPBrowse() as needed.
    - select_timeout(): Take LDAP browse refresh value into
      account.

git-svn-id: svn+ssh://src.apple.com/svn/cups/cups.org/trunk@5157 7a7537e8-13f0-0310-91df-b6672ffda945