BUG/MINOR: quic: fix uninit list on show quic handler
A recent patch has extended "show quic" capability. It is now possible
to list a specific list of connections, either active frontend, closing
frontend or backend connections.
An issue was introduced as the list is local storage. As this command is
reentrant, show quic context must be extended so that the currently
inspected list is also saved.
This issue was reported via GCC which mentions an uninitilized value
depending on branching conditions.