relay: Disable relay_periodic when the relay module is disabled

Closes ticket 32244.

changes/ticket32244

@@ -0,0 +1,3 @@
+  o Code simplification and refactoring:
+    - Disable relay_periodic when the relay module is disabled.
+      Closes ticket 32244.

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_periodic.c	\
 	src/feature/relay/relay_sys.c		\
 	src/feature/relay/router.c		\
 	src/feature/relay/routerkeys.c		\
@@ -174,6 +173,7 @@ LIBTOR_APP_TESTING_A_SOURCES = $(LIBTOR_APP_A_SOURCES)
 MODULE_RELAY_SOURCES = 						\
 	src/feature/relay/routermode.c				\
 	src/feature/relay/relay_config.c			\
+	src/feature/relay/relay_periodic.c			\
 	src/feature/relay/transport_config.c
 
 # The Directory Authority module.

src/feature/relay/relay_periodic.h

@@ -12,7 +12,20 @@
 #ifndef TOR_FEATURE_RELAY_RELAY_PERIODIC_H
 #define TOR_FEATURE_RELAY_RELAY_PERIODIC_H
 
+#ifdef HAVE_MODULE_RELAY
+
 void relay_register_periodic_events(void);
 void reschedule_descriptor_update_check(void);
 
+#else
+
+#include "lib/cc/compat_compiler.h"
+
+#define relay_register_periodic_events() \
+  STMT_NIL
+#define reschedule_descriptor_update_check() \
+  STMT_NIL
+
+#endif
+
 #endif /* !defined(TOR_FEATURE_RELAY_RELAY_PERIODIC_H) */