[PATCH v5.5.670] maintain DynaLoader::dl_{librefs,modules}

when XSLoader falls back to DynaLoader, it wipes out
@dl_{librefs,modules}, breaking dl_unload_all_files()

this was triggered by something worthing noting, some of the xs module
.pms are not installed in the arch lib, for example Data::Dumper is here:
/usr/local/devperl/lib/5.5.670/Data/Dumper.pm
instead of the expected:
/usr/local/devperl/lib/5.5.670/i686-linux/Data/Dumper.pm

it seems any module with a two::level namespace is not installed into the
arch lib, but those with one level (e.g. B.pm, IO.pm) are in the arch lib.

--- DynaLoader.pm~      Sun Mar  5 14:31:30 2000
+++ DynaLoader.pm       Sun Mar  5 15:09:03 2000
@@ -58,8 +58,8 @@
 @dl_require_symbols = ();       # names of symbols we need
 @dl_resolve_using   = ();       # names of files to link with
 @dl_library_path    = ();       # path to look for files
-@dl_librefs         = ();       # things we have loaded
-@dl_modules         = ();       # Modules we have loaded
+#@dl_librefs         = ();       # things we have loaded
+#@dl_modules         = ();       # Modules we have loaded
 
 # This is a fix to support DLD's unfortunate desire to relink -lc
 @dl_resolve_using = dl_findfile('-lc') if $dlsrc eq "dl_dld.xs";

• [PATCH v5.5.670] maintain DynaLoader::dl_{librefs,modules} by Doug MacEachern