Roll SPIRV-Tools and add build_overrides/spirv_tools.gni

To allow embedding SPIRV-Tools in multiple projects (Chromium, ANGLE,
Skia, Dawn) we added overridable variables that replace hardcoded paths
to dependencies.

BUG=chromium:870747

Change-Id: I2041528305739035b46c700719386597bd9b553a
Reviewed-on: https://chromium-review.googlesource.com/1162239Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581252}

BUILD.gn

@@ -142,7 +142,7 @@ group("gn_all") {
       "//ppapi/examples/video_encode",
       "//printing:printing_unittests",
       "//third_party/SPIRV-Tools/src:SPIRV-Tools",
-      "//third_party/SPIRV-Tools/src/testing/fuzzers",
+      "//third_party/SPIRV-Tools/src/test/fuzzers",
       "//third_party/cacheinvalidation:cacheinvalidation_unittests",
       "//third_party/pdfium/samples:pdfium_test",
       "//third_party/webrtc/rtc_tools:frame_analyzer",

DEPS

@@ -213,7 +213,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'spv_tools_revision': 'd38a0a3b4476798744c4223acbefab3af97698fd',
+  'spv_tools_revision': '2d9a325264e3fc81317acc0a68a098f0546c352d',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.

build_overrides/spirv_tools.gni

+# Copyright 2018 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# We are building inside Chromium
+spirv_tools_standalone = false
+
+# Paths to SPIRV-Tools dependencies in Chromium
+spirv_tools_googletest_dir = "//third_party/googletest/src"
+spirv_tools_spirv_headers_dir = "//third_party/spirv-headers/src"