Print undemanglable symbols in vndk-vtable-dumper

Instead of skipping the vtable entry, vndk-vtable-dumper now prints
undemanglable vtable entries.
Vtables should always contain C++ symbols (mangled symbols). The only
exceptions are when vtables contain pure virtual or deleted
virtual functions. In that case the vtable may contain C symbols
(unmangled symbols) of __cxa_pure_virtual or __cxa_deleted_virtual.
In that case we just print the undemanglable C symbol as its mangled and
demangled name, though technically its not mangled.

Bug: 111968285
Test: m vndk-vtable-dumper
Test: vndk-vtable-dumper android.frameworks.displayservice@1.0.so
Test: vndk-vtable-dumper android.frameworks.displayservice@1.0.so -mangled
Change-Id: I4d1c99ba23a327fd5709233a38d309180c9cfd43