CamelObject: Suppress state file warnings for old IMAP accounts.
CamelObject: Suppress state file warnings for old IMAP accounts.

CamelImapFolder had a persistent "check-folder" property whose value was
recorded in Camel's binary state files under tag 0x2500.  This property
is not present in CamelIMAPXFolder, but we may still be reading the tag
for accounts that were migrated from IMAP to IMAPX.  Check for that tag
value while reading state files and suppress the runtime warning.

matzipan/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server