apply extend/os to migrate_gcc_dependents_if_needed

Library/Homebrew/cmd/update-report.rb

@@ -9,6 +9,7 @@ require "description_cache_store"
 require "cli/parser"
 require "settings"
 require "linuxbrew-core-migration"
+require "extend/os/update-report"
 
 module Homebrew
   extend T::Sig
@@ -293,8 +294,6 @@ module Homebrew
   end
 
   def migrate_gcc_dependents_if_needed
-    # TODO: Refactor and move to extend/os
-    return if OS.mac? # rubocop:disable Homebrew/MoveToExtendOS
     return if Settings.read("gcc-rpaths.fixed") == "true"
 
     Formula.installed.each do |formula|

Library/Homebrew/extend/os/mac/update-report.rb

@@ -0,0 +1,12 @@
+# typed: false
+# frozen_string_literal: true
+
+module Homebrew
+  extend T::Sig
+
+  module_function
+
+  def migrate_gcc_dependents_if_needed
+    # do nothing
+  end
+end

Library/Homebrew/extend/os/update-report.rb

@@ -0,0 +1,4 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "extend/os/mac/update-report" if OS.mac?