might caused by https://chromium-review.googlesource.com/#/c/chromiumos/overlays/chromiumos-overlay/+/609423/

from manojgupta: 
  The CL should  not have been reverted https://chromium-review.googlesource.com/#/c/chromiumos/overlays/chromiumos-overlay/+/609423/
  The underlying issue of '-nostdlib++' has been fixed by cherry picking an upstream CL which adds support for this
  flag but needs chromiumos-sdk builder to upload new toolchain prebuilts (which shouldb e done in 2 hr from now).
  But it requires CL:609423 for it to work.

from yunlian:
  CL:609423 relanded as CL:610520