Update ninja to v1.8.0.

New binaries for Mac, Linux32, Linux64, Windows.  Also update shell script.
See the bug for how these were built.
The main "new" thing is performance improvement when building chrome with goma.

After confirming the the behavior of ninja 1.8.0 on buildbot, I will roll ninja 1.8.1 includes fix for non-deterministic test.

TBR=dpranke@chromium.org
Bug: 761691, 738186
Change-Id: I108996dccfdf5d95d8815d6cece5eba46f3e8178
Reviewed-on: https://chromium-review.googlesource.com/648372
Commit-Queue: Takuto Ikuta <tikuta@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>

ninja

@@ -12,7 +12,7 @@ cat <<-EOF
 No prebuilt ninja binary was found for this system.
 Try building your own binary by doing:
   cd ~
-  git clone https://github.com/martine/ninja.git -b v1.7.2
+  git clone https://github.com/martine/ninja.git -b v1.8.0
   cd ninja && ./configure.py --bootstrap
 Then add ~/ninja/ to your PATH.
 EOF