relay: Disable relay_sys when the relay module is disabled

Closes ticket 32245.

changes/ticket32245

@@ -0,0 +1,3 @@
+  o Code simplification and refactoring:
+    - Disable relay_sys when the relay module is disabled.
+      Closes ticket 32245.

src/app/main/subsystem_list.c

@@ -18,7 +18,6 @@
 #include "core/or/or_sys.h"
 #include "core/or/orconn_event_sys.h"
 #include "feature/control/btrack_sys.h"
-#include "feature/relay/relay_sys.h"
 #include "lib/compress/compress_sys.h"
 #include "lib/crypt_ops/crypto_sys.h"
 #include "lib/err/torerr_sys.h"
@@ -33,6 +32,7 @@
 #include "lib/evloop/evloop_sys.h"
 
 #include "feature/dirauth/dirauth_sys.h"
+#include "feature/relay/relay_sys.h"
 
 #include <stddef.h>
 
@@ -66,7 +66,9 @@ const subsys_fns_t *tor_subsystems[] = {
   &sys_mainloop,
   &sys_or,
 
+#ifdef HAVE_MODULE_RELAY
   &sys_relay,
+#endif
 
 #ifdef HAVE_MODULE_DIRAUTH
   &sys_dirauth,

src/core/include.am

@@ -143,7 +143,6 @@ LIBTOR_APP_A_SOURCES = 				\
 	src/feature/relay/dns.c			\
 	src/feature/relay/ext_orport.c		\
 	src/feature/relay/onion_queue.c		\
-	src/feature/relay/relay_sys.c		\
 	src/feature/relay/router.c		\
 	src/feature/relay/routerkeys.c		\
 	src/feature/relay/selftest.c		\
@@ -174,6 +173,7 @@ MODULE_RELAY_SOURCES = 						\
 	src/feature/relay/routermode.c				\
 	src/feature/relay/relay_config.c			\
 	src/feature/relay/relay_periodic.c			\
+	src/feature/relay/relay_sys.c				\
 	src/feature/relay/transport_config.c
 
 # The Directory Authority module.

src/feature/dirauth/dirauth_sys.h

@@ -12,6 +12,10 @@
 #ifndef DIRAUTH_SYS_H
 #define DIRAUTH_SYS_H
 
+#ifdef HAVE_MODULE_DIRAUTH
+
 extern const struct subsys_fns_t sys_dirauth;
 
+#endif
+
 #endif /* !defined(DIRAUTH_SYS_H) */

src/feature/relay/relay_sys.h

@@ -12,6 +12,10 @@
 #ifndef TOR_FEATURE_RELAY_RELAY_SYS_H
 #define TOR_FEATURE_RELAY_RELAY_SYS_H
 
+#ifdef HAVE_MODULE_RELAY
+
 extern const struct subsys_fns_t sys_relay;
 
+#endif
+
 #endif /* !defined(TOR_FEATURE_RELAY_RELAY_SYS_H) */