BUG/MEDIUM: connection: fix memory corruption when building a proxy v2 header

Use temporary trash chunk, instead of global trash chunk in
make_proxy_line_v2() to avoid memory overwrite.

This fix must also be backported to 1.5.
(cherry picked from commit 77d1f0143e210c13ee8ec6aaf6b3150fa4ce6c5b)
1 file changed