r21496: A number of ldb control and LDAP changes, surrounding the

r21496: A number of ldb control and LDAP changes, surrounding the
'phantom_root' flag in the search_options control

- Add in support for LDB controls to the js layer
- Test the behaviour
- Implement support for the 'phantom_root' flag in the partitions module
- Make the LDAP server set the 'phantom_root' flag in the search_options control
  - This replaces the global_catalog flag passed down as an opaque pointer
- Rework the string-format control parsing function into
  ldb_parse_control_strings(), returning errors by ldb_errorstring()
  method, rather than with printf to stderr
- Rework some of the ldb_control handling logic

Andrew Bartlett
(This used to be commit 2b3df7f38d7790358dbb4de1b8609bf794a351fb)