[PATH] fix c/10962, slow lookup_field

[Jason Merrill]

Thanks, almost there.

I wouldn't bother with the DECL_DECLARES_TYPE_NON_TEMPLATE_P macro; it
doesn't make the code any clearer.  Just write the test directly in the
function.

Also, we need a more descriptive name than "lang_record_type" for this
struct.  Perhaps sorted_fields_type?

Don't add another blank line before struct lang_type.

Jason