default to forking system on non-windows

src/switch_core.c

@@ -1431,8 +1431,9 @@ SWITCH_DECLARE(switch_status_t) switch_core_init(switch_core_flag_t flags, switc
 	switch_set_flag((&runtime.dummy_cng_frame), SFF_CNG);
 	switch_set_flag((&runtime), SCF_AUTO_SCHEMAS);
 	switch_set_flag((&runtime), SCF_CLEAR_SQL);
+#ifdef WIN32
 	switch_set_flag((&runtime), SCF_THREADED_SYSTEM_EXEC);
-
+#endif
 	switch_set_flag((&runtime), SCF_NO_NEW_SESSIONS);
 	runtime.hard_log_level = SWITCH_LOG_DEBUG;
 	runtime.mailer_app = "sendmail";