BUG/MAJOR: http: null-terminate the http actions keywords list

Commit a0dc23f ("MEDIUM: http: implement http-request set-{method,path,query,uri}")
forgot to null-terminate the list, resulting in crashes when these actions
are used if the platform doesn't pad the struct with nulls.

Thanks to Gunay Arslan for reporting a detailed trace showing the
origin of this bug.

No backport to 1.5 is needed.
1 file changed