(ITS#7533) Don't install DB_CONFIG.example if built w/o back-hdb or back-bdb

[quanah@OpenLDAP.org]

Full_Name: Quanah Gibson-Mount
Version: 2.4.33
OS: Linux 2.6
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (74.196.25.250)


When building without BDB support, DB_CONFIG.example is still copied to the
state directory.  Given a lack of BDB support, this seems pointless.

installing slapd.ldif in /opt/zimbra/openldap-2.4.33.4z/etc/openldap
../../build/shtool install -c  -m 600 slapd.ldif.tmp
/opt/zimbra/openldap-2.4.33.4z/etc/openldap/slapd.ldif
../../build/shtool install -c  -m 600 ./DB_CONFIG \
                /opt/zimbra/openldap-2.4.33.4z/var/openldap-data/DB_CONFIG.example
../../build/shtool install -c  -m 600 ./DB_CONFIG \
                /opt/zimbra/openldap-2.4.33.4z/etc/openldap/DB_CONFIG.example
../../build/shtool mkdir -p /opt/zimbra/openldap-2.4.33.4z/etc/openldap/schema