review compilation options for new major version of OpenLDAP

[davidcoutadeur]

The new major version of OpenLDAP is an opportunity to review the compilation options.

Some options must be removed:

• maybe tcpwrappers, which are less and less used and source of problems?

Some options must be added / replaced

[coudot]

See also #28

[coudot]

Some work done in 9b375eacfa5fcc011e4fe07a3aa20ebe745a3484

TODO:

• Need libevent >= 2.1 for lload, not available on CentOS 7
• Check lload status to restart it automatically

[davidcoutadeur]

• libevent-ltb is provided conditionally for CentOS 7 packages.
• lload is stopped only if started before. (see c7257aa)

[davidcoutadeur]

seems everything is ok