Promote debug.rb to default gems.

It have no upstream repo yet. This change is experimental for 3.0.0-preview2.

doc/maintainers.rdoc

@@ -38,8 +38,6 @@ Zachary Scott (zzak)
 
 === Libraries
 
-[lib/debug.rb]
-  _unmaintained_
 [lib/mkmf.rb]
   _unmaintained_
 [lib/rubygems.rb, lib/rubygems/*]
@@ -101,6 +99,8 @@ Zachary Scott (zzak)
 [lib/English.rb]
   _unmaintained_
   https://github.com/ruby/English
+[lib/debug.rb]
+  _unmaintained_
 [lib/delegate.rb]
   _unmaintained_
   https://github.com/ruby/delegate

doc/standard_library.rdoc

@@ -8,7 +8,6 @@ description.
 
 == Libraries
 
-DEBUGGER__:: Debugging functionality for Ruby
 MakeMakefile:: Module used to generate a Makefile for C extensions
 RbConfig:: Information of your configure and build of Ruby
 Gem:: Package management framework for Ruby
@@ -33,6 +32,7 @@ Benchmark:: Provides methods to measure and report the time used to execute code
 Bundler:: Manage your Ruby application's gem dependencies
 CGI:: Support for the Common Gateway Interface protocol
 CSV:: Provides an interface to read and write CSV files and data
+DEBUGGER__:: Debugging functionality for Ruby
 Delegator:: Provides three abilities to delegate method calls to an object
 DidYouMean:: "Did you mean?" experience in Ruby
 Digest:: Provides a framework for message digest libraries

lib/debug.gemspec

@@ -0,0 +1,22 @@
+Gem::Specification.new do |spec|
+  spec.name          = "debug"
+  spec.version       = "0.1.0"
+  spec.authors       = ["Yukihiro Matsumoto"]
+  spec.email         = ["matz@ruby-lang.org"]
+
+  spec.summary       = %q{Debugging functionality for Ruby}
+  spec.description   = %q{Debugging functionality for Ruby}
+  spec.homepage      = "https://github.com/ruby/debug"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+end