[boost] [typeof] please make "*_native" tests expected failures on HP-UX

Like many other compilers, aCC6 on HP-UX does not support typeof extension (to be precise, it supports it in GNU C++ dialect compatibility mode -- -Ag++ -- but not in the default mode). In explicit-failures-markup.xml, there is a group of toolsets making "*_native" typeof library tests expected failures, with the remark: "Native mode is not supported for this compiler.". Please, add "acc" toolset to this group, in both HEAD and the RC branch. I don't think that a patch is needed for such a simple change, but if you need/want a patch, I can provide one. Thanks, Boris