Found with bin/find-unneeded-includes a few low hanging
boost/optional headers.
This gets us about 75M includebloat reduction; still much to go

Change-Id: I5c737631767970f9145609aad298a5d11e3fed65
Reviewed-on: https://gerrit.libreoffice.org/59840
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>