Roll src/third_party/SPIRV-Tools/src 615918c91d1d..4517c7b883c5 (4 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git/+log/615918c91d1d..4517c7b883c5

git log 615918c91d1d..4517c7b883c5 --date=short --no-merges --format='%ad %ae %s'
2019-10-23 stevenperron@google.com Update DEPS (#2986)
2019-10-22 afdx@google.com spirv-fuzz: fuzzer pass to adjust memory access operands (#2968)
2019-10-22 greg@lunarg.com Instrument: Add missing def-use analysis. (#2985)
2019-10-22 afdx@google.com spirv-fuzz: add missing functionality for matrix composites (#2974)

Also rolling transitive DEPS:
  src/third_party/spirv-headers/src 842ec9067462..af64a9e826bf

Created with:
  gclient setdep -r src/third_party/SPIRV-Tools/src@4517c7b883c5

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/spirv-tools-chromium-autoroll
Please CC radial-bots+chrome-roll@google.com,jonahr@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_angle_vk32_deqp_rel_ng;luci.chromium.try:android_angle_vk32_rel_ng;luci.chromium.try:android_angle_vk64_deqp_rel_ng;luci.chromium.try:android_angle_vk64_rel_ng;luci.chromium.try:linux_angle_deqp_rel_ng;luci.chromium.try:linux-angle-rel;luci.chromium.try:win-angle-rel-32;luci.chromium.try:win-angle-rel-64;luci.chromium.try:win-angle-deqp-rel-32;luci.chromium.try:win-angle-deqp-rel-64
TBR=radial-bots+chrome-roll@google.com,jonahr@google.com

Bug: None
Change-Id: I1c253ed78593e4e7ba3e8977f8e01a5d5d15fe25
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1877856Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#708961}

DEPS

@@ -294,11 +294,11 @@ 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': '615918c91d1d6ae1620f3ab3c03de1acba3cce0e',
+  'spv_tools_revision': '4517c7b883c56d9d1ef34f67b42fedd3f008f3dd',
   # 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_headers_revision': '842ec90674627ed2ffef609e3cd79d1562eded01',
+  'spv_headers_revision': 'af64a9e826bf5bb5fcd2434dd71be1e41e922563',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.