Merge branch 'fix-struct-linger' @jbech "Accidentally disabled by 0dda56a due to confusion between struct linger vs. SO_LINGER and #define vs. AC_DEFINE. Try adding synthetic #error test to confirm." * fix-struct-linger: cmake: check for 'struct linger' existence test/bench*: prefix event-config.h macros after 0dda56a48e94 test/bench_httpclient: restore SO_LINGER usage after 0dda56a48e94 Fixes: #444 (original pull-request)