BUG/MINOR: hq-interop: fix transcoding of wrapping response buffer

BUG/MINOR: hq-interop: fix transcoding of wrapping response buffer

The below patch has implemented support for response wrapping in HTTP/0.9
transcoder, similar to what is already performed in HTTP/3.

  1e144c488c612092067e07f18618482c64d33d17
  BUG/MINOR: hq-interop: support response buffer wrapping

However, some bits were incorrectly written and the transcoding would
not be able to handle all of the wrapping data in one pass, despite no
crash possible. This patch fixes these, so that a wrapping response can
be handled in a single pass by the HTTP/0.9 transcoder if there is
enough room in the output HTX buffer.

This should fix github issue #3430.

This should be backported up to 3.3.