bug#6988: __HAS_MIMEOLE overlaps __MIMEOLE_MS, may hit non-MSFT MUA, don't use __HAS_MIMEOLE in MSFT-only message rules

git-svn-id: https://svn.apache.org/repos/asf/spamassassin/trunk@1554308 13f79535-47bb-0310-9956-ffa450edef68