Build auto_index tool with USE="tools"
See also: https://bugs.gentoo.org/529066

--- tools/Jamfile.v2.orig	2023-08-08 21:02:48 UTC
+++ tools/Jamfile.v2
@@ -18,6 +18,7 @@ TOOLS =
     ;
 
 TOOLS =
+    auto_index/build//auto_index
     bcp//bcp
     inspect/build//inspect
     quickbook//quickbook