Repackaged VS 2017 with updated Debuggers

Due to bugs in the Fall Creators Update SDK we can't build Chromium with
clang with that SDK. However the debuggers package (windbg and friends)
in the "spring" Creators Update SDK can't handle fastlink PDBs reliably.

So, this repackages the previous toolchain with the debuggers package
from the Fall Creators Update SDK.

This makes no difference to the builds, although it does mean that an
updated copy of dbghelp.dll will be copied to the build directories.

I created this package by manually copying over the new debuggers
directory and then running:

    python package_from_installed.py --repackage=...

Bug: 773476
Change-Id: I05b37d518e3700e125eee5bbcb2cbf885d01afc5
Reviewed-on: https://chromium-review.googlesource.com/827629Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524481}

build/vs_toolchain.py

@@ -340,8 +340,9 @@ def _GetDesiredVsToolchainHashes():
   to build with."""
   env_version = GetVisualStudioVersion()
   if env_version == '2017':
-    # VS 2017 Update 3.2 with 10.0.15063.468 SDK and patched setenv.cmd.
-    return ['a9e1098bba66d2acccc377d5ee81265910f29272']
+    # VS 2017 Update 3.2 with 10.0.15063.468 SDK, patched setenv.cmd, and
+    # 10.0.16299.15 debuggers.
+    return ['1180cb75833ea365097e279efb2d5d7a42dee4b0']
   raise Exception('Unsupported VS version %s' % env_version)