Move eu-strip from third_party/ to buildtools/third_party/

The build and builtools directories are provided to standalone projects
such as angle. Move eu-strip into buildtools so that those projects'
copy of build/ can find it.

BUG=angleproject:2475
TEST=build standalone angle with target_os="fuchsia"
NOPRESUBMIT=true

Change-Id: If3d6b9027bd01cdc67db5ef825a304016bd77a7d
Reviewed-on: https://chromium-review.googlesource.com/c/1427781
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#627463}
12 files changed