As xnheap_size() changed, a sanity check in xnheap_mmap fails now, at
least for SVN head, maybe also 2.2.x.

I would suggest the following patch to fix this, though I'm not 100%
sure its correct in all cases (do we ever come across a heap of multiple
extents in xnheap_mmap?).

Jan


PS: I'll spent a beer (or two...) for the one who starts writing a
testsuite for the native skin - in user-space, please, to catch also
issues like this one.