Revert __malloc_initialize_hook symbol poisoning

It turns out the Emacs-internal malloc implementation uses
__malloc_* symbols.  If glibc poisons them in <stdc-pre.h>,
Emacs will no longer compile.

ChangeLog

@@ -1,3 +1,15 @@
+2016-06-20  Florian Weimer  <fweimer@redhat.com>
+
+	Revert symbol poisoning of  __malloc_initialize_hook.
+	* include/stdc-predef.h (__malloc_initialize_hook): Remove
+	poisoning.
+	* malloc/Makefile: Remove un-poisoning.
+	* malloc/arena.c (ptmalloc_init): Use __malloc_initialize_hook
+	instead of old__malloc_initialize_hook.
+	* malloc/malloc-hooks.h: Likewise.
+	* malloc/malloc.c: Likewise.
+	* malloc/mcheck-init.c: Likewise.
+
 2016-06-19  Carlos O'Donell  <carlos@redhat.com>
 
 	* sysdeps/unix/sysv/linux/times.c (__times): Expand comments.

include/stdc-predef.h

@@ -57,11 +57,4 @@
 /* We do not support C11 <threads.h>.  */
 #define __STDC_NO_THREADS__		1
 
-/* Remove symbols from the API which can be interposed.  */
-#if defined (__GNUC__)
-# if __GNUC__ >= 4
-#  pragma GCC poison __malloc_initialize_hook
-# endif	 /* __GNUC__ >= 4 */
-#endif	/* __GNUC__ */
-
 #endif

malloc/Makefile

@@ -115,20 +115,6 @@ endif
 
 include ../Rules
 
-# Support references to removed APIs.  We use #pragma GCC poison in
-# <stdc-predef.h> to make it difficult to reference them.  For select
-# source files, we work around this poisoning by defining a macro on
-# the command line (which is processed before <stdc-predef.h> and can
-# therefore use tokens poisoned later).
-poisoned_apis = \
-  __malloc_initialize_hook \
-
-unpoisoned_api_defines := \
-  $(foreach sym,$(poisoned_apis), \
-    $(patsubst %,-Dold%, $(sym))=$(sym))
-CPPFLAGS-malloc.c = $(unpoisoned_api_defines)
-CPPFLAGS-mcheck-init.c = $(unpoisoned_api_defines)
-
 CFLAGS-mcheck-init.c = $(PIC-ccflag)
 CFLAGS-obstack.c = $(uses-callbacks)
 

malloc/arena.c

@@ -341,7 +341,7 @@ ptmalloc_init (void)
         __malloc_check_init ();
     }
 #if HAVE_MALLOC_INIT_HOOK
-  void (*hook) (void) = atomic_forced_read (old__malloc_initialize_hook);
+  void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook);
   if (hook != NULL)
     (*hook)();
 #endif

malloc/malloc-hooks.h

@@ -19,9 +19,6 @@
 #ifndef _MALLOC_HOOKS_H
 #define _MALLOC_HOOKS_H
 
-/* These hooks are no longer part of the public API and are poisoned
+void (*__malloc_initialize_hook) (void);
-   in <stdc-predef.h>.  Their names here reflect the command-line
-   mapping which is used inside glibc to get past the poisoning.  */
-void (*old__malloc_initialize_hook) (void);
 
 #endif  /* _MALLOC_HOOKS_H */

malloc/malloc.c

@@ -1851,9 +1851,9 @@ static void *memalign_hook_ini (size_t alignment, size_t sz,
                                 const void *caller) __THROW;
 
 #if HAVE_MALLOC_INIT_HOOK
-void weak_variable (*old__malloc_initialize_hook) (void) = NULL;
+void weak_variable (*__malloc_initialize_hook) (void) = NULL;
-compat_symbol (libc, old__malloc_initialize_hook,
+compat_symbol (libc, __malloc_initialize_hook,
-	       old__malloc_initialize_hook, GLIBC_2_0);
+	       __malloc_initialize_hook, GLIBC_2_0);
 #endif
 
 void weak_variable (*__free_hook) (void *__ptr,

malloc/mcheck-init.c

@@ -27,4 +27,4 @@ turn_on_mcheck (void)
   mcheck (NULL);
 }
 
-void (*old__malloc_initialize_hook) (void) = turn_on_mcheck;
+void (*__malloc_initialize_hook) (void) = turn_on_mcheck;