[ruby/win32-registry] Use pathspecs to select needed files in the gem file

Exclude other git management files too.

ruby/win32-registry@3be0188111

Author: nobu

ext/win32/win32-registry.gemspec

@@ -17,13 +17,10 @@ Gem::Specification.new do |spec|
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   excludes = %w[
     bin/ test/ spec/ features/ rakelib/
-    .git .github .mailmap appveyor Rakefile Gemfile
+    .git* .mailmap appveyor Rakefile Gemfile
   ]
-  spec.files = Dir.chdir(__dir__) do
-    `git ls-files -z`.split("\x0").reject do |f|
-      File.identical?(f, __FILE__) || f.start_with?(*excludes)
-    end
-  end
+  git_files = %w[git ls-files -z --] + excludes.map {|x| ":^/#{x}"}
+  spec.files = IO.popen(git_files, chdir: __dir__, &:read).split("\x0")
   spec.bindir = "exe"
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]