Pull new GN, update toolchain definitions

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of "src").
 #
@@ skipping 55 matching lines @@
   # the commit queue can handle CLs rolling openssl
   # and whatever else without interference from each other.
   "openssl_revision": "284247",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
   "angle_revision": "bc75f36b04c8bab99bcecf8cdca16ecee3ac58ee",
   # 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": "48edf30c463fc41fb9fb0926f8466b473cb177fa",
+  "buildtools_revision": "f79f8ef8691cb0c91ecf36392f6defabd824af60",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFIum
   # and whatever else without interference from each other.
   "pdfium_revision": "635e82ec20b3d5ffcb24f9a1b1be9f1f24d8a3f4",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling openmax_dl
   # and whatever else without interference from each other.
   "openmax_dl_revision": "6925",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
@@ skipping 739 matching lines @@
     # migration completes (let's say Sep 1 2014).
     "name": "check_git_config",
     "pattern": ".",
     "action": [
         "python",
         "src/tools/check_git_config.py",
         "--running-as-hook",
     ],
   },
 ]