"Remove pow() splitting and cleanup backends" luajit commit reproducers.

repro1.sh

src/luajit -Ohotloop=1 -Ohotexit=1 -Orecunroll=1 -Ocallunroll=1 -e"
return (function (Name0)
        return (function (Name0)
          Name0 = 'Name' ;
          return ((-#(-(113 ^ -(113.473426 .. 0) .. 0) .. -0.000181) .. 0.000000 .. -0.000000)) {  }, { Name = { Name0 = -'Name' } }                           
        end){}
end){}
"
# luajit: lj_record.c:142: rec_check_slots: Assertion `lj_obj_equal(tv, &tvk)' failed.
# Aborted