(ITS#5762) ldap_create_page_control might return wrong error code

[ralf@OpenLDAP.org]

Full_Name: Ralf Haferkamp
Version: RE24, Head
OS: Linux
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (89.166.241.0)
Submitted by: ralf


ldap_create_page_control_value doesn't reset ld_errno to LDAP_SUCCESS therefor
it will return the result code of the previous LDAP API call instead of
LDAP_SUCCESS. (If the previous LDAP API call set ld_errno do something different
than LDAP_SUCCESS).

The same seems to be true for the corresponding function in at least:
sortctrl.c, vlvctrl.c and stctrl.c

Fix will follow.