configure: Don't print disable option for module that can't be disabled

This is currently for the dircache module that can not be disabled by itself,
it is only disabled from the relay module.

Thus, we should not print in the configure summary the disable option.

Signed-off-by: David Goulet <dgoulet@torproject.org>

configure.ac

@@ -357,6 +357,12 @@ dnl ---
 dnl All our modules.
 m4_define(MODULES, relay dirauth dircache)
 
+# Some modules are only disabled through another option. For those, we don't
+# want to print the help in the summary at the end of the configure. Any entry
+# in the following set will not print the "--disable-module-NAME" command in
+# the summary.
+m4_set_add_all([MODULES_WITH_NO_OPTIONS], [dircache])
+
 dnl Relay module.
 AC_ARG_ENABLE([module-relay],
               AS_HELP_STRING([--disable-module-relay],
@@ -2821,7 +2827,9 @@ PPRINT_SUBTITLE([Modules])
 m4_foreach_w([mname], MODULES,
   [
     AM_COND_IF(m4_join([], [BUILD_MODULE_], m4_toupper([]mname[])), value=1, value=0)
-    PPRINT_PROP_BOOL([mname (--disable-module-mname)], $value)
+    m4_set_contains([MODULES_WITH_NO_OPTIONS], mname,
+                    PPRINT_PROP_BOOL([mname], $value),
+                    PPRINT_PROP_BOOL([mname (--disable-module-mname)], $value))
   ]
 )