Roll SPIRV-Tools from c278dada96d9 to 2c60d16a646b (2 revisions)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git/+log/c278dada96d9..2c60d16a646b

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-angle-autoroll
Please CC cwallez@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

Bug: None
Tbr: cwallez@google.com
Change-Id: I73b49238c919ab04427e096fc89e0a1ffa805c98
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2391056
Reviewed-by: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 20d1fd2..740027e 100644
--- a/DEPS
+++ b/DEPS
@@ -80,7 +80,7 @@
   'spirv_headers_revision': '3fdabd0da2932c276b25b9b4a988ba134eba1aa6',
 
   # Current revision of SPIRV-Tools for Vulkan.
-  'spirv_tools_revision': 'c278dada96d98310ce0bf2dc50b14c85f197568b',
+  'spirv_tools_revision': '2c60d16a646b7b4d1541e278dda7133cf6feaa9b',
 
   # Current revision of Khronos Vulkan-Headers.
   'vulkan_headers_revision': 'ced848d699b5673a7df900bcfe0b1a6ba9e989ce',