Copy new attribute types when linking. bfd will copy attributes as needed,
however it will fail to output them if the type is not set correctly. This
can happen when it finds an attribute it hasn't seen before, for example
when building shared objects it will use the attributes from crti.o, hwever
this file has no attributes set.

Differential Revision: https://reviews.freebsd.org/D2413
Reviewed by: imp