buffer: reword Buffer.concat error message
buffer: reword Buffer.concat error message

this brings the error messaging in line with
other node TypeError messages.

Fixes: https://github.com/joyent/node/issues/7766
PR-URL: https://github.com/joyent/node/pull/8723
Reviewed-By: James M Snell <2d64a127ffc94dbe6295928a16bedf8b26814159@users.noreply.github.com>
Reviewed-By: Colin Ihrig <838f779c91673db29b8572ea3f54d191d3878ae2@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node