talloc.[ch]: remove "type safety" hack that violates C types

The destructors used by talloc take a "void *" first parameter.
However talloc.h had a #define hack that treated the destructor as a
function taking first parameter of type "typeof(ptr)" where ptr is the
pointer the destructor is set for. I suppose this was done to add some
kind of "type safety" against adding a destructor expecting another
type of pointer; however this hack is questionable and violates the
real C level typing. Remove the hack from the header and adjust
talloc.c to avoid a warning about a C type violation that became
visible after removing the hack.

Author: Uoti Urpala

talloc.c

@@ -432,8 +432,9 @@ int talloc_increase_ref_count(const void *ptr)
 
   this is referenced by a function pointer and should not be inline
 */
-static int talloc_reference_destructor(struct talloc_reference_handle *handle)
+static int talloc_reference_destructor(void *ptr)
 {
+	struct talloc_reference_handle *handle = ptr;
 	struct talloc_chunk *ptr_tc = talloc_chunk_from_ptr(handle->ptr);
 	_TLIST_REMOVE(ptr_tc->refs, handle);
 	return 0;

talloc.h

@@ -70,20 +70,15 @@ typedef void TALLOC_CTX;
    if we have a recent gcc */
 #if (__GNUC__ >= 3)
 #define _TALLOC_TYPEOF(ptr) __typeof__(ptr)
-#define talloc_set_destructor(ptr, function)				      \
-	do {								      \
-		int (*_talloc_destructor_fn)(_TALLOC_TYPEOF(ptr)) = (function);	      \
-		_talloc_set_destructor((ptr), (int (*)(void *))_talloc_destructor_fn); \
-	} while(0)
 /* this extremely strange macro is to avoid some braindamaged warning
    stupidity in gcc 4.1.x */
 #define talloc_steal(ctx, ptr) ({ _TALLOC_TYPEOF(ptr) __talloc_steal_ret = (_TALLOC_TYPEOF(ptr))_talloc_steal((ctx),(ptr)); __talloc_steal_ret; })
 #else
-#define talloc_set_destructor(ptr, function) \
-	_talloc_set_destructor((ptr), (int (*)(void *))(function))
 #define _TALLOC_TYPEOF(ptr) void *
 #define talloc_steal(ctx, ptr) (_TALLOC_TYPEOF(ptr))_talloc_steal((ctx),(ptr))
 #endif
+#define talloc_set_destructor(ptr, function) \
+	_talloc_set_destructor((ptr), (function))
 
 #define talloc_reference(ctx, ptr) (_TALLOC_TYPEOF(ptr))_talloc_reference((ctx),(ptr))
 #define talloc_move(ctx, ptr) (_TALLOC_TYPEOF(*(ptr)))_talloc_move((ctx),(void *)(ptr))