Copy the mtime on puppet generate types

When installing a new module it can maintain the file timestamps from
the original tarball (like g10 does). puppet generate types uses the
timestamp of when it ran.

If you update a module to a release that was created before it ran
puppet types generate, it will never update the types. This can happen
with a module downgrade, or just when you regenerated types manually. By
using --force the timestamps are ignored, but that's only a workaround.

This new approach copies the mtime from the source file to the generated
cache file. It is only considered up to date if the mtime matches.

lib/puppet/generate/type.rb

@@ -49,7 +49,7 @@ def format=(format)
         # @return [Boolean] Returns true if the output is up-to-date or false if not.
         def up_to_date?(outputdir)
           f = effective_output_path(outputdir)
-          Puppet::FileSystem::exist?(f) && (Puppet::FileSystem::stat(@path) <=> Puppet::FileSystem::stat(f)) <= 0
+          Puppet::FileSystem::exist?(f) && (Puppet::FileSystem::stat(@path) <=> Puppet::FileSystem::stat(f)) == 0
         end
 
         # Gets the filename of the output file.
@@ -240,6 +240,7 @@ def self.generate(inputs, outputdir = nil, force = false)
             Puppet::FileSystem.open(effective_output_path, nil, 'w:UTF-8') do |file|
               file.write(result)
             end
+            Puppet::FileSystem.touch(effective_output_path, mtime: Puppet::FileSystem::stat(input.path).mtime)
           rescue Exception => e
             @bad_input = true
             Puppet.log_exception(e, _("Failed to generate '%{effective_output_path}': %{message}") % { effective_output_path: effective_output_path, message: e.message })