Use TracePoint.allow_reentry when available

This fixes compatibility with TracePoint users such as Zeitwerk

Test script:

```ruby
require 'fileutils'
FileUtils.mkdir_p('/tmp/lib/foo')
File.write('/tmp/lib/foo.rb', 'module Foo; end')
File.write('/tmp/lib/foo/bar.rb', 'Foo::Bar = 1')

require 'zeitwerk'

loader = Zeitwerk::Loader.new
loader.push_dir('/tmp/lib')
loader.setup

require 'debug'
binding.break
p Foo::Bar
```

before:
```
[8, 16] in /tmp/debug-zeitwerk.rb
     8| loader = Zeitwerk::Loader.new
     9| loader.push_dir('/tmp/lib')
    10| loader.setup
    11|
    12| require 'debug'
=>  13| binding.break
    14| p Foo::Bar
    15|
    16| p :done
=>#0    <main> at /tmp/debug-zeitwerk.rb:13
(rdbg) p Foo::Bar    # command
eval error: uninitialized constant Foo::Bar
  (rdbg)//tmp/debug-zeitwerk.rb:1:in `<main>'
=> nil
```

after:
```
[8, 16] in /tmp/debug-zeitwerk.rb
     8| loader = Zeitwerk::Loader.new
     9| loader.push_dir('/tmp/lib')
    10| loader.setup
    11|
    12| require 'debug'
=>  13| binding.break
    14| p Foo::Bar
    15|
    16| p :done
=>#0    <main> at /tmp/debug-zeitwerk.rb:13
(rdbg) p Foo::Bar    # command
=> 1
```

lib/debug/thread_client.rb

@@ -356,6 +356,16 @@ def instance_eval_for_cmethod frame_self, src
       [:return_value,     "_return"],
     ]
 
+    def eval_with_binding(binding, src)
+      if binding
+        f, _l = binding.source_location
+        binding.eval(src, "(rdbg)/#{f}")
+      else
+        frame_self = current_frame.self
+        instance_eval_for_cmethod(frame_self, src)
+      end
+    end
+
     def frame_eval src, re_raise: false
       @success_last_eval = false
 
@@ -365,13 +375,12 @@ def frame_eval src, re_raise: false
         b.local_variable_set(name, var) if /\%/ !~ name
       end
 
-      result = if b
-                  f, _l = b.source_location
-                  b.eval(src, "(rdbg)/#{f}")
-                else
-                  frame_self = current_frame.self
-                  instance_eval_for_cmethod(frame_self, src)
-                end
+      result = if TracePoint.respond_to?(:allow_reentry)
+        TracePoint.allow_reentry { eval_with_binding(b, src) }
+      else
+        eval_with_binding(b, src)
+      end
+
       @success_last_eval = true
       result