At least on IA64 and PowerPC 64-bit ELFv1, the functions are stored in
the .text sections but they are accessed through a function descriptor
stored in a data section, for example for PowerPC 64-bit ELFv1 that
section is called .opd.

We should take this into account when checking the n_type for the
functions we have requested information from nlist().

Rationale-by: James Clarke <jrtc27@jrtc27.com>