Guest C built with -fexceptions binds __gcc_personality_v0 to
__gcc_personality_v0_nid_postfix, and the unwinder recognizes the frame
by that address. exception_c_cleanup links the host personality, so it
passed without the export.
The new test builds a call-site table by hand and drives the routine the
way the unwinder does: through the _nid_postfix symbol and through
CallPersonality. It covers the cleanup phase installing the landing pad,
the search phase continuing, ranges before and after the call site, a
call site with no landing pad, no LSDA, a signal frame, an unsupported
version, and an unknown personality. Without the export it fails to link.
mugurc