roll deps (KhronosGroup#6076)

* Roll external/abseil_cpp/ bcf4bf315..c8d5854f0 (18 commits)

abseil/abseil-cpp@bcf4bf3...c8d5854

Created with:
  roll-dep external/abseil_cpp

* Roll external/spirv-headers/ 8c88e0c4c..8e82b7cfe (1 commit)

KhronosGroup/SPIRV-Headers@8c88e0c...8e82b7c

Created with:
  roll-dep external/spirv-headers

---------

Co-authored-by: GitHub Actions[bot] <>

Author: github-actions[bot]

DEPS

@@ -3,7 +3,7 @@ use_relative_paths = True
 vars = {
   'github': 'https://github.com',
 
-  'abseil_revision': 'bcf4bf315ab25075b51ad1bca9da351aa4579c00',
+  'abseil_revision': 'c8d5854f0ba521701455281b17f5f24cf584f916',
 
   'effcee_revision': '874b47102c57a8979c0f154cf8e0eab53c0a0502',
 
@@ -14,7 +14,7 @@ vars = {
 
   're2_revision': 'c84a140c93352cdabbfb547c531be34515b12228',
 
-  'spirv_headers_revision': '8c88e0c4c94a21de825efccba5f99a862b049825',
+  'spirv_headers_revision': '8e82b7cfeca98baae9a01a53511483da7194f854',
 }
 
 deps = {