remove init::headers

[Will Coleda]

Can anyone see a reason why we have a config step (init::headers) to
generate this list of files? Looks like it's just grepping  through
the MANIFEST to find them -

They are then thrown on the "big pile" of headers in GENERAL_H_FILES,
and (incorrectly) in the PMC dependencies. Even if they were used
correctly, there's no reason to generate the list dynamically.

Unless someone sees some value here, I'll rip this out in a branch.

-- 
Will "Coke" Coleda