config: make config_var_is_dumpable static.

src/app/config/confparse.c

@@ -614,7 +614,7 @@ config_var_is_listable(const config_var_t *var)
  * This option may be set because a variable is hidden, or because it is
  * derived from another variable which will already be written out.
  **/
-bool
+static bool
 config_var_is_dumpable(const config_var_t *var)
 {
   if (config_var_is_derived(var)) {

src/app/config/confparse.h

@@ -191,7 +191,6 @@ void warn_deprecated_option(const char *what, const char *why);
 
 bool config_var_is_settable(const config_var_t *var);
 bool config_var_is_listable(const config_var_t *var);
-bool config_var_is_dumpable(const config_var_t *var);
 
 /* Helper macros to compare an option across two configuration objects */
 #define CFG_EQ_BOOL(a,b,opt) ((a)->opt == (b)->opt)