don't assume decoders have the buffer attribute
don't assume decoders have the buffer attribute

Summary:
The default encoding for cmd.exe is "cp437", the original DOS codepage,
and the decoder for that is one of the ones that doesn't have an
accessible buffer attribute.

Reviewers: sean

Differential Revision: https://phabricator.buildinspace.com/D111

scalp42/peru,enzochiau/peru,scalp42/peru,oconnor663/peru,ierceg/peru,buildinspace/peru,nivertech/peru,ierceg/peru,oconnor663/peru,nivertech/peru,olson-sean-k/peru,enzochiau/peru,olson-sean-k/peru,buildinspace/peru