Fix to replace deprecated macro APIs with Ruby-prefixed ones

[gemmaro]

Hello,

This replaces deprecated macro APIs like Qnil with newer Ruby-prefixed ones like RUBY_Qnil.

The scope of this pull request is: FIXNUM_P, IMMEDIATE_P, NIL_P, SPECIAL_CONST_P, STATIC_SYM_P, Qfalse, Qnil, Qtrue, and Qundef. They has been deprecated at the following commit:

b0a7c0dfd04ac51b621c016387d5f65cfe3ecf5a
Author:     卜部昌平 <shyouhei@ruby-lang.org>
AuthorDate: Fri Jan 15 16:34:34 2021 +0900
Commit:     卜部昌平 <shyouhei@ruby-lang.org>
CommitDate: Fri Sep 10 20:00:06 2021 +0900

Parent:     818fabfcd9 include/ruby/internal/stdalign.h: add doxygen
Contained:  master mkmf/deterministic
Follows:    v3_0_0_rc2 (3095)
Precedes:   v3_1_0_preview1 (1943)

include/ruby/internal/special_consts.h: add doxygen

Must not be a bad idea to improve documents. [ci skip]

And the current EOL version of Ruby is 3.1.7, so I think this changeset is natural.

(There is a full list of deprecated macro APIs, but this PR doesn't cover them all.)

RSpec tests pass with Ruby 3.4 locally:

$ RUBYLIB=_test/lib rspec _test
..............

Finished in 3.87 seconds (files took 0.06831 seconds to load)
14 examples, 0 failures

with the following patch:

diff --git a/_config.yml b/_config.yml
index b22869f..0136226 100644
--- a/_config.yml
+++ b/_config.yml
@@ -5,4 +5,4 @@ markdown: kramdown
 permalink: /:categories/:title/
 kramdown:
   parse_block_html: true
-rbversion: 3.0
+rbversion: 3.4
diff --git a/_test/lib/c_api.rb b/_test/lib/c_api.rb
index 575476a..fe7d6d0 100644
--- a/_test/lib/c_api.rb
+++ b/_test/lib/c_api.rb
@@ -1,7 +1,7 @@
 require 'open3'
 require 'tempfile'
 
-BUILD_VERSION = "3.0"
+BUILD_VERSION = "3.4"
 
 module CAPI
   class Result

Thank you,