perf symbols: Remove incorrect open-coded container_of()

At least on ARM, padding is inserted between rb_node and sym in struct
symbol_name_rb_node, causing "((void *)sym) - sizeof(struct rb_node)" to
point inside rb_node rather than to the symbol_name_rb_node. Fix this
by converting the code to use container_of().

Cc: Ian Munsie <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Ming Lei <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Tom Zanussi <[e-mail]>
LKML-Reference: <20101123163106.GA25677@debian>
Signed-off-by: Rabin Vincent <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/symbol.c

···
 {
 	struct rb_node **p = &self->rb_node;
 	struct rb_node *parent = NULL;
-	struct symbol_name_rb_node *symn = ((void *)sym) - sizeof(*parent), *s;
+	struct symbol_name_rb_node *symn, *s;
+
+	symn = container_of(sym, struct symbol_name_rb_node, sym);
 
 	while (*p != NULL) {
 		parent = *p;