[PATCH] MINOR: stream: initialize the current_rule field to NULL on stream init (no replies)

I stumbled upon a minor valgrind warning when testing a SSL change:

==16783== Conditional jump or move depends on uninitialised value(s)
==16783== at 0x44E662: http_res_get_intercept_rule (proto_http.c:3730)
==16783== by 0x44E662: http_process_res_common (proto_http.c:6528)
==16783== by 0x4797B7: process_stream (stream.c:1851)
==16783== by 0x414634: process_runnable_tasks (task.c:238)
==16783== by 0x40B02F: run_poll_loop (haproxy.c:1528)
==16783== by 0x407F25: main (haproxy.c:1887)

It looks like it's currently possible for the current_rule field to be
evaluated before being set, probably since commit
152b81e7b2565862956af883820d4f79177d0651.

--
Remi