BUG/MINOR: mux_h2: missing space between "st" and ".flg" in the "show fd" helper

BUG/MINOR: mux_h2: missing space between "st" and ".flg" in the "show fd" helper

That was causing confusing outputs like this one whenan H2S is known:

   1030 : ... last_h2s=0x2ed8390 .id=775 .st=HCR.flg=0x4001 .rxbuf=...
                                                ^^^^

This was introduced by commit ab2ec4540 in 2.1-dev2 so the fix can be
backported as far as 2.1.

(cherry picked from commit ed4464e6c698bfb410610b7f3850cd0fa3331eb1)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 1c694698bc378224165860000f5e41b3301a9be7)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 663c62c31e45eac5b6b0c4b3d4b24d6a8151e5c8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>