extend/kernel: add missing utils require.

Don't require this globally to avoid slowing down boot.

Library/Homebrew/extend/kernel.rb

@@ -264,6 +264,8 @@ def with_custom_locale(locale, &block)
 
  # Kernel.system but with exceptions.
  def safe_system(cmd, *args, **options)
+ require "utils"
+
  return if Homebrew.system(cmd, *args, **options)
 
  raise ErrorDuringExecution.new([cmd, *args], status: $CHILD_STATUS)
@@ -273,6 +275,8 @@ def safe_system(cmd, *args, **options)
  #
  # @api internal
  def quiet_system(cmd, *args)
+ require "utils"
+
  Homebrew._system(cmd, *args) do
  # Redirect output streams to `/dev/null` instead of closing as some programs
  # will fail to execute if they can't write to an open stream.