* ks/hipe_bif-remove_refs_from/OTP-10851:
  Fixed test to allow for lists:foreach/2 call
  Change the return value of hipe_bifs:remove_refs_from/1

It produced the same result as file:read_link/1.

* sc/gen_tcp_send_error_closed/OTP-10839:
  Fix type of error Reason on gen_tcp:send/2

* bjorn/stdlib/types:
  Make the file:filename() type more restrictive
  c: Remove handling of binaries in return from file:list_dir/1

The recommended type for filenames is a list of characters (which
may be Unicode characters greater than 255). Change the
file:filename() to reflect that.

For the filename module we still need a type that can be either
a string or a binary, so we need to introduce the type
file:filename_all().

In order to avoid an ummatched return warning in erts and make the code
more sane, the return value of the bif was changed from [] to 'ok'.
(Probably more hipe_bifs need such changes but they will have to wait.)

While at it, the code of various functions in hipe_unified_loader was
shortened by using lists:foreach/1 instead of explicit recursion.