BUG/MEDIUM: payload: ensure that a request channel is available

Denys Fedoryshchenko reported a segfault when using certain
sample fetch functions in the "tcp-request connection" rulesets
despite the warnings. This is because some tests for the existence
of the channel were missing.

The fetches which were fixed are :
  - req.ssl_hello_type
  - rep.ssl_hello_type
  - req.ssl_sni

This fix must be backported to 1.5.
(cherry picked from commit 83f2592bcd2e186beeabcba16be16faaab82bd39)
1 file changed