nlist - get namelist entries
int nlist(const char *file, struct nlist nl)
Nlist() fills fields n_sclass and n_value of array nl with values found
in the non-stripped executable file, whose n_name strings are identical
to those in nl. Entries in nl that are not found have their
n_value/n_sclass fields set to 0.
Nl ends with an entry with a null pointer or empty string n_name.
The return value is -1 on failure, else the number of entries not found