Memory leak with TracePoint on bmethod

[Bug #20194]

When disabling the TracePoint on bmethod, the hooks list is not freed.

For example:

    obj = Object.new
    obj.define_singleton_method(:foo) {}
    bmethod = obj.method(:foo)
    tp = TracePoint.new(:return) {}

    10.times do
      100_000.times do
        tp.enable(target: bmethod) {}
      end

      puts `ps -o rss= -p #{$$}`
    end

Before:

    18208
    22832
    26528
    29728
    34000
    37776
    40864
    44400
    47680
    51504

After:

    16688
    17168
    17168
    17248
    17696
    17760
    17824
    17824
    17856
    17920

1 files changed, 1 insertions, 0 deletions

diff --git a/vm_trace.c b/vm_trace.c
index fb896fd423..9d0507879f 100644
--- a/vm_trace.c
+++ b/vm_trace.c
@@ -1259,6 +1259,7 @@ rb_tracepoint_enable_for_target(VALUE tpval, VALUE target, VALUE target_line)
             (tp->events & (RUBY_EVENT_CALL | RUBY_EVENT_RETURN))) {
             if (def->body.bmethod.hooks == NULL) {
                 def->body.bmethod.hooks = ZALLOC(rb_hook_list_t);
+                def->body.bmethod.hooks->is_local = true;
             }
             rb_hook_list_connect_tracepoint(target, def->body.bmethod.hooks, tpval, 0);
             rb_hash_aset(tp->local_target_set, target, Qfalse);