[openchange]Missing attribute in openchange schema brake replication

Hello,

We had a person on samba-technical mailing list complaining about 
replication issues when openchange schema is added.
After some investigation I discovered that he add replication issue 
because its schema was broken.

The reason why the schema is broken is because openchange lacked an 
attribute and use a control to relax checks and samba had a too much 
relaxed check for the mayContain attribute.

The missing attribute is:
#
dn: CN=msExch-Proxy-Gen-Options,${SCHEMADN}
objectClass: top
objectClass: attributeSchema
cn: msExch-Proxy-Gen-Options
attributeID: 1.2.840.113556.1.4.7000.102.50044
attributeSyntax: 2.5.5.9
isSingleValued: TRUE
showInAdvancedViewOnly: TRUE
adminDisplayName: msExch-Proxy-Gen-Options
adminDescription: msExch-Proxy-Gen-Options
oMSyntax: 2
searchFlags: 0
lDAPDisplayName: msExchProxyGenOptions
name: msExch-Proxy-Gen-Options
schemaIDGUID: 974c9a02-33fc-11d3-aa6e-00c04f8eedd8
isMemberOfPartialAttributeSet: FALSE
objectCategory: CN=Attribute-Schema,${SCHEMADN}