Roll buildtools 222bd42ce3..11961c2151

  In order to roll GN 6a9b6b43..16920f1d (r370714:r371631) and pick up
  the following changes:

  81aa4e8f Add an assert_no_deps variable to GN.
  bf5ff790 Support for excluding variable from forwarding via forward_variables_form.

TBR=dpranke@chromium.org
CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_dbg;tryserver.chromium.win:win8_chromium_gn_dbg,win_chromium_gn_x64_rel

Review URL: https://codereview.chromium.org/1639983002

Cr-Commit-Position: refs/heads/master@{#371670}

DEPS

@@ -55,7 +55,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.
-  'buildtools_revision': '222bd42ce39d1bd8f08fe089b066f49c469e1cdf',
+  'buildtools_revision': '11961c21510b90aa6057064459a1af53f3fff449',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.