BUG/MINOR: mux-h1: Fix test instead a BUG_ON() in h1_send_error()

In the previous patch (86924532db "BUG/MINOR: mux-h1: Fix test instead a
BUG_ON() in h1_send_error()"), a BUG_ON() condition was inverted by error in
h1_send_error(). The stream-connector must be NULL to be able to destroy the H1
stream.

This patch must be backported with the commit above (to 2.7).
1 file changed