message: Add -Wno-error to cflags.
diff: '<(absl_srcdir)/synchronization/internal/create_thread_identity.cc',
  '<(absl_srcdir)/synchronization/internal/create_thread_identity.cc',
  '<(absl_srcdir)/synchronization/internal/graphcycles.cc',
  - '<(absl_srcdir)/synchronization/internal/graphcycles.cc',
  '<(absl_srcdir)/synchronization/internal/per_thread_sem.cc',
  '<(absl_srcdir)/synchronization/internal/waiter.cc',
  '<(absl_srcdir)/synchronization/mutex.cc',
  '<(absl_srcdir)/synchronization/notification.cc',
  ],
  + 'cflags': [
  + '-Wno-error',
  + ],
  'dependencies': [
  'absl_base',
  'absl_debugging',
  