Build GN with c++11.

GN code does not need GNU extensions to be built like some other
Chromium code.

BUG=427584
TEST=./tools/gn/bootstrap/bootstrap.py, the manual part still works.
R=brettw@chromium.org

Review URL: https://codereview.chromium.org/1358243003

Cr-Original-Commit-Position: refs/heads/master@{#350558}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1f9152a906db2d2b2967a77cbcca5614068c1116
1 file changed
tree: 36f6a715ce0025ca61d395266a7028ddabb3673e
  1. tools/