becoming X86_64_SSE_CLASS/X86_64_INTEGER_CLASS/... This is not defined in
    the ABI because there sizeof(extended)=16 and hence the class of the upper
    eightbyte of the extended value can never be merged with the class of
    another field (except in a union, but then the class of the lower
    eightbyte will also be overwritten).

    Handle it the same as when the lower eightbyte class of an extended in an
    aggregate gets changed into something else: pass everything in memory
    (part of mantis #26993)

git-svn-id: trunk@28984 -