Roll buildtools 5378d73123..e84114dbe2

  In order to roll GN e5510883..b17c5d23 (r387371:r388502) and pick up
  the following changes:

  fb8986d4 GN: Make write_runtime_deps take effect only a target is resolved
  e4b98e2d Fix GN freeze on generating Visual Studio projects
  440b117b Add arflags to GN
  31500019 GN: Use std::unique_ptr for owned pointers in VisualStudioWriter.
  959ec4e4 GN: Use std::unique_ptr for owning pointers in InputFileManager.
  f9b6b5ae GN: Use std::unique_ptr in Loader::ToolchainRecordMap.
  ac5bf2c0 GN: Use std::unique_ptr for owning pointers in Scope::NamedScopeMap.
  647a1af2 GN: Use std::unique_ptr for owned pointers in ImportManager.
  6ce99c70 GN: Replace vector<ParseNode*> with vector<unique_ptr<ParseNode>> in parse_tree.h.
  c065bd83 gn: Use .obj extension for pch objects on Windows.
  8ea3910c [MIPS] Fix gn_unittests LoaderTest.Foo test
  a67a258a Make it easy to run `gn format' on an emacs buffer.
  3a93fa5a Add shell=True for gn-format.py on Windows

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/1909523002

Cr-Commit-Position: refs/heads/master@{#388529}

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': '5378d73123b64907773cc5c1bb027b2f765ff00a',
+  'buildtools_revision': 'e84114dbe2b65428951c876349b6a3ff1afbfccd',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.