GCC gives C code built with -fexceptions, and cleanup-only functions
after link-time optimization, the C personality __gcc_personality_v0.
The unwinder accepted only its own C++ personality, so an exception
thrown through such a frame was never caught.
libc now provides the C personality, which never catches and installs
the frame's cleanup landing pad in the cleanup phase, and the unwinder
calls it for those frames.
Dean Galvin