libctf, types: enhance ctf_type_aname to print function arg types

libctf, types: enhance ctf_type_aname to print function arg types

Somehow this never got implemented, which makes debugging any kind of
bug that has to do with argument types fantastically confusing, because
it *looks* like the func type takes no arguments though in fact it does.

This also lets us simplify the dumper slightly (and introduces our first
uses of ctf_assert and ctf_err_warn: there will be many more).

ctf_type_aname dumps function types without including the function
pointer name itself: ctf_dump search-and-replaces it in.  This seems to
give the nicest-looking results for existing users of both, even if it
is a bit fiddly.

libctf/
	* ctf-types.c (ctf_type_aname): Print arg types here...
	* ctf-dump.c (ctf_dump_funcs): ... not here: but do substitute
	in the type name here.