move libevent into base

This simplifies the process of bootstrapping gn standalone.

And libevent is not really used outside of base. base is actually its only client.

BUG=569352
TEST=See CL for details for how to reproduce this.
R=thestig@chromium.org
TBR=cpu@chromium.org

Review URL: https://codereview.chromium.org/1531573008

Cr-Original-Commit-Position: refs/heads/master@{#366282}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: c7ebe6daa79da2e351345065020cc7f216126f15
1 file changed
tree: 0cac9849cbc962f8f53d3984b290d1ced3867e7d
  1. tools/