Try again to fix the links in the GN README.md.

Turns out that gitiles is even more broken than I thought, and
using absolute paths for links doesn't work either. This patch
changes the links in GN's README.md to use full URLs instead.

TBR=nodir@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1394433004

Cr-Original-Commit-Position: refs/heads/master@{#353682}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: c8bcd19882e5f0ba62badf0ebd2efde625531c7e
1 file changed
tree: 6d6405f767e6f3cc69dd5899f2b0d85f173467cb
  1. tools/