This helps to reduce repetition in code. Instead of doing "TYPE_*"
everywhere, you can do `include Fiddle::Types`, and write the type name
directly.

This PR is to help reduce repetition when writing Fiddle code. Right now
we have to type `TYPE_` everywhere, and you also have to include all of
`Fiddle` to access `TYPE_*` constants. With this change, you can just
include `Fiddle::Types` and it will shorten your code and also you only
have to include those constants.

Here is an example before:

```ruby
require "fiddle"

module MMAP
  # All Fiddle constants included
  include Fiddle

  def self.make_function name, args, ret
    ptr = Handle::DEFAULT[name]
    func = Function.new ptr, args, ret, name: name
    define_singleton_method name, &func.to_proc
  end

  make_function "munmap", [TYPE_VOIDP, # addr
                           TYPE_SIZE_T], # len
                           TYPE_INT

  make_function "mmap", [TYPE_VOIDP,
                         TYPE_SIZE_T,
                         TYPE_INT,
                         TYPE_INT,
                         TYPE_INT,
                         TYPE_INT], TYPE_VOIDP

  make_function "mprotect", [TYPE_VOIDP, TYPE_SIZE_T, TYPE_INT], TYPE_INT
end
```

After:

```ruby
require "fiddle"

module MMAP
  # Only type names included
  include Fiddle::Types

  def self.make_function name, args, ret
    ptr = Fiddle::Handle::DEFAULT[name]
    func = Fiddle::Function.new ptr, args, ret, name: name
    define_singleton_method name, &func.to_proc
  end

  make_function "munmap", [VOIDP, # addr
                           SIZE_T], # len
                           INT

  make_function "mmap", [VOIDP, SIZE_T, INT, INT, INT, INT], VOIDP

  make_function "mprotect", [VOIDP, SIZE_T, INT], INT
end
```

We only need to import the type names, and you don't have to type
`TYPE_` over and over. I think this makes Fiddle code easier to read.

https://github.com/ruby/fiddle/commit/49fa7233e5

Co-authored-by: Sutou Kouhei <kou@clear-code.com>

This commit adds constants for unsigned values. Currently we can use `-`
to mean "unsigned", but I think having a specific name makes Fiddle more
user friendly. This commit continues to support `-`, but introduces
negative constants with "unsigned" names

I think this will help to eliminate [this
code](https://github.com/ruby/ruby/blob/3a56bf0bcc66e14ffe5ec89efc32ecfceed180f4/lib/mjit/c_type.rb#L31-L38)

https://github.com/ruby/fiddle/commit/2bef0f1082

Co-authored-by: Sutou Kouhei <kou@clear-code.com>

https://github.com/ruby/fiddle/commit/c5abcc3a7e

I don't use tool/sync_default_gem.rb because the last sync was incomplete.

Co-authored-by: Hiroshi SHIBATA <hsbt@ruby-lang.org>
Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>
Co-authored-by: sinisterchipmunk <sinisterchipmunk@gmail.com>
Co-authored-by: Sutou Kouhei <kou@clear-code.com>

https://github.com/ruby/fiddle/commit/6d24fb5438

See comment for details.

https://github.com/ruby/fiddle/commit/0c76f03dc4

* Add a "pinning" reference

A `Fiddle::Pinned` objects will prevent the objects they point to from
moving.  This is useful in the case where you need to pass a reference
to a C extension that keeps the address in a global and needs the
address to be stable.

For example:

```ruby
class Foo
  A = "hi" # this is an embedded string

  some_c_function A # A might move!
end
```

If `A` moves, then the underlying string buffer may also move.
`Fiddle::Pinned` will prevent the object from moving:

```ruby
class Foo
  A = "hi" # this is an embedded string

  A_pinner = Fiddle::Pinned.new(A) # :nodoc:

  some_c_function A # A can't move because of `Fiddle::Pinned`
end
```

This is a similar strategy to what Graal uses:

  https://www.graalvm.org/sdk/javadoc/org/graalvm/nativeimage/PinnedObject.html#getObject--

* rename global to match exception name

* Introduce generic Fiddle::Error and rearrange error classes

Fiddle::Error is the generic exception base class for Fiddle exceptions.
This commit introduces the class and rearranges Fiddle exceptions to
inherit from it.

https://github.com/ruby/fiddle/commit/ac52d00223

For example, :voidp equals to Fiddle::TYPE_VOID_P.

https://github.com/ruby/fiddle/commit/3b4de54899

Add rb_fiddle_ prefix to conversion functions.h to keep backward
compatibility but value_to_generic() isn't safe for TYPE_CONST_STRING
and not String src. Use rb_fiddle_value_to_generic() instead.

https://github.com/ruby/fiddle/commit/0ffcaa39e5