(ITS#4733) back-config should populate defaults

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: 2.3/HEAD
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (76.168.84.21)
Submitted by: hyc


If a minimal LDIF is slapadd'd to create the slapd configuration, any parameters
that are not specified on input will take on their default values. However,
these defaults will not be present in the config entries and will not be visible
upon subsequent slapcat/ldapsearch.

It would be nicer if after each entry is loaded from slapd.d and parsed, the
entire entry is regenerated internally, with all defaults populated.