Added constructors to block_address_translation and segment_descriptor
that will clear its memory (could be done more efficiently though, it just
uses memset()).
Added definitions for the MSR (machine state register).
Added tlbsync() macro (direct assembler call).
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5092 a95241bf-73f2-0310-859d-f6bbb57e9c96