CLEANUP: muxes: Remove useless if condition in show_fd function

In H1, H2 and FCGI muxes, in the show_fd function, there is duplicated test on
the stream's subs field.

This patch fixes the issue #1142. It may be backported as far as 2.2.

(cherry picked from commit 6c93c4ef089fc79ce4e85fa0d9e7f61720291dba)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
3 files changed