`drop_privileges` should be file local scope.

src/mosquitto.c

@@ -73,7 +73,7 @@ int deny_severity = LOG_INFO;
  * Note that setting config->user to "root" does not produce an error, but it
  * strongly discouraged.
  */
-int drop_privileges(struct mosquitto__config *config)
+static int drop_privileges(struct mosquitto__config *config)
 {
 #if !defined(__CYGWIN__) && !defined(WIN32)
 	struct passwd *pwd;

src/mosquitto_broker_internal.h

@@ -678,8 +678,6 @@ int config__read(struct mosquitto__config *config, bool reload);
 void config__cleanup(struct mosquitto__config *config);
 int config__get_dir_files(const char *include_dir, char ***files, int *file_count);
 
-int drop_privileges(struct mosquitto__config *config);
-
 /* ============================================================
  * Server send functions
  * ============================================================ */