Roll SPIRV-Tools from f15133788010 to fc8264854c53 (5 revisions)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git/+log/f15133788010..fc8264854c53

2020-10-06 afdx@google.com spirv-fuzz: Replace dead-block terminators with OpKill etc. (#3882)
2020-10-06 vasniktel@gmail.com spirv-fuzz: TransformationPropagateInstructionDown (#3692)
2020-10-06 afdx@google.com spirv-fuzz: Transformation to add wrappers for OpKill and similar (#3881)
2020-10-06 afdx@google.com spirv-fuzz: Use overflow ids when duplicating regions (#3878)
2020-10-06 vasniktel@gmail.com spirv-fuzz: Fix rvalue references (#3883)

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,timvp@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/+doc/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,timvp@google.com
Change-Id: Ib4ad31f2422336dd942227d2a437492930b65310
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2455298Reviewed-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@{#814618}

DEPS

@@ -302,7 +302,7 @@ 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': 'f15133788010b25b859a87fd82c60a4d6448fefc',
+  'spv_tools_revision': 'fc8264854c5346da631a54831e9f34926987eff6',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.