Using pre-cached type_infos provided by the typeid operator seems to work now

Apparently there was no problem in this after all. The reason it
seemed not to work earlier was because of the unwinding failure due to
the missing .cfi_startproc and .cfi_endproc thingies in helper.s

The hack in ucbhelper is now not needed after all.

Change-Id: If9fec5c502d4c9d0c44709ad9c2729f812e882e2