Because NaCl and PNaCl are already sunset status.
  see https://bugs.chromium.org/p/chromium/issues/detail?id=239656#c160

  configure.ac: Patch for this file was provided by @nobu.

  [Feature #14041][ruby-core:83497][fix GH-1726]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60374 b2dd03c8-39d4-4d8f-98ff-823fe69b080e