oc: Enforce the folder creation mapping when the FID exists

We believe the folder ID OpenChange is sending us is new
and we keep the indexing database properly updated.

Although the solution is not elegant, this could avoid
inconsistencies between what the client stores and the
relation in the MAPIStore backend.

OpenChange/MAPIStoreMapping.h

@@ -60,6 +60,8 @@
                     andFlags: (uint8_t) flags;
 - (void) updateID: (uint64_t) idNbr
           withURL: (NSString *) urlString;
+- (BOOL) updateURL: (NSString *) urlString
+            withID: (uint64_t) idNbr;
 
 @end