If `Class#allocate` is prohibited, subclasses should also be implicitly prohibited.
```ruby
p Class.new(Struct).allocate.class
# => #<Class:0x82362ac00> by #6122
# => allocator undefined for #<Class:0x000000083a983220> (TypeError) by Ruby 3.2
```
Added `MRB_DEFINE_ALLOCATOR()` to allow subclasses to use `Class#allocate`.
Supplement to #6122.
The method introduced by #5979 causes a fault by swapping classes.
```console
% bin/mruby -e 'Method = Proc; p Object.method(:inspect)'
zsh: segmentation fault (core dumped) bin/mruby -e 'Method = Proc; p Object.method(:inspect)'
```
After applying this patch, a `TypeError` exception will be raised.
```console
% bin/mruby -e 'Method = Proc; p Object.method(:inspect)'
trace (most recent call last):
[1] -e:1
-e:1:in method: allocation failure of Proc (TypeError)
```
However, if the `mrb_vtype` is the same object, the same care must still be taken as before.
```console
% bin/mruby -e 'Method = Binding; p method(:puts).eval("12345")'
trace (most recent call last):
[1] -e:1
-e:1:in eval: wrong argument type nil (expected Proc) (TypeError)
```
Calling `Class#allocate` with `UnboundMethod#bind_call` usually succeeds without problems.
If this behavior does not make us happy, we can now prohibit it with `MRB_SET_INSTANCE_TT(klass, MRB_TT_UNDEF)`.
At the same time, it applies to the `Binding`, `Complex`, `Data`, `Float`, `Integer`, `Method`, `Rational` and `UnboundMethod` classes.
- raise ArgumentError if arguments size differs from data size.
Previously it accepted smaller argument size.
- the message is updated to "wrong number of arguments". It's not
"struct" any longer.
Yukihiro "Matz" Matsumoto