Make the recommend_pkg file dirauth-only.

src/core/include.am

@@ -157,7 +157,6 @@ LIBTOR_APP_A_SOURCES += 			\
 	src/feature/dirauth/dsigs_parse.c	\
 	src/feature/dirauth/guardfraction.c	\
 	src/feature/dirauth/reachability.c	\
-	src/feature/dirauth/recommend_pkg.c	\
 	src/feature/dirauth/process_descs.c	\
 	src/feature/dirauth/voteflags.c
 
@@ -180,6 +179,7 @@ MODULE_DIRAUTH_SOURCES = 					\
 	src/feature/dirauth/dirauth_sys.c			\
 	src/feature/dirauth/dircollate.c			\
 	src/feature/dirauth/dirvote.c				\
+	src/feature/dirauth/recommend_pkg.c			\
 	src/feature/dirauth/shared_random.c			\
 	src/feature/dirauth/shared_random_state.c
 

src/feature/dirauth/recommend_pkg.h

@@ -12,6 +12,18 @@
 #ifndef TOR_RECOMMEND_PKG_H
 #define TOR_RECOMMEND_PKG_H
 
+#ifdef HAVE_MODULE_DIRAUTH
 int validate_recommended_package_line(const char *line);
 
+#else
+
+static inline int
+validate_recommended_package_line(const char *line)
+{
+  (void) line;
+  return 0;
+}
+
+#endif
+
 #endif