[glibc] Remove spurious references to _dl_open_hook

[Florian Weimer <fw@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=032712621fd376def8ee4c1d997b414f29a30108

commit 032712621fd376def8ee4c1d997b414f29a30108
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Aug 1 15:49:07 2022 +0200

    Remove spurious references to _dl_open_hook
    
    _dl_open_hook was removed in commit 466c1ea15f461edb8e3ffaf5d86d708
    ("dlfcn: Rework static dlopen hooks").
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 libio/vtables.c | 4 ----
 malloc/arena.c  | 5 -----
 2 files changed, 9 deletions(-)

diff --git a/libio/vtables.c b/libio/vtables.c
index 499f0039cb..50acab7f21 100644
--- a/libio/vtables.c
+++ b/libio/vtables.c
@@ -25,10 +25,6 @@
 
 void (*IO_accept_foreign_vtables) (void) attribute_hidden;
 
-/* Used to detected multiple libcs.  */
-extern struct dl_open_hook *_dl_open_hook;
-libc_hidden_proto (_dl_open_hook);
-
 #else  /* !SHARED */
 
 /* Used to check whether static dlopen support is needed.  */
diff --git a/malloc/arena.c b/malloc/arena.c
index 0a684a720d..defd25c8a6 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -300,11 +300,6 @@ next_env_entry (char ***position)
 #endif
 
 
-#ifdef SHARED
-extern struct dl_open_hook *_dl_open_hook;
-libc_hidden_proto (_dl_open_hook);
-#endif
-
 #if USE_TCACHE
 static void tcache_key_initialize (void);
 #endif