Roll external/abseil_cpp/ 9dc9586ef..2d77015ec (21 commits)

abseil/abseil-cpp@9dc9586...2d77015

Created with:
  roll-dep external/abseil_cpp

Author: GitHub Actions[bot]

DEPS

@@ -3,7 +3,7 @@ use_relative_paths = True
 vars = {
   'github': 'https://github.com',
 
-  'abseil_revision': '9dc9586effb94a41f9471de61278bfcd62964da1',
+  'abseil_revision': '2d77015ec852f90f04444eedaacb846ffc187174',
 
   'effcee_revision': '514b52ec61609744d7e587d93a7ef9b60407ab45',