[Bug #18264] Fix memory leak in TracePoint

TracePoint leaks memory because it allocates a `rb_tp_t` struct
without ever freeing it (it is created with `RUBY_TYPED_NEVER_FREE`).

test/ruby/test_settracefunc.rb

@@ -564,6 +564,16 @@ class TestSetTraceFunc < Test::Unit::TestCase
     }
   end
 
+  # Bug #18264
+  def test_tracpoint_memory_leak
+    assert_no_memory_leak([], <<-PREP, <<-CODE, rss: true)
+code = proc { TracePoint.new(:line) { } }
+1_000.times(&code)
+PREP
+1_000_000.times(&code)
+CODE
+  end
+
   def trace_by_set_trace_func
     events = []
     trace = nil

vm_trace.c

@@ -748,7 +748,7 @@ tp_memsize(const void *ptr)
 
 static const rb_data_type_t tp_data_type = {
     "tracepoint",
-    {tp_mark, RUBY_TYPED_NEVER_FREE, tp_memsize,},
+    {tp_mark, RUBY_TYPED_DEFAULT_FREE, tp_memsize,},
     0, 0, RUBY_TYPED_FREE_IMMEDIATELY
 };