Update ninja to v1.6.0 on Mac, Linux32, Linux64, Windows.

See the bug for how these were built.

The linux binaries were built by thestig@chromium.org.
The windows binary was built by scottmg@chromium.org.
The mac binary was built by thakis@chromium.org

BUG=505508
TBR=maruel@chromium.org

Review URL: https://codereview.chromium.org/1221683003

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@295863 0039d316-1c4b-4281-b951-d872f2087c98

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 v1.5.3
+  git clone https://github.com/martine/ninja.git -b v1.6.0
   cd ninja && ./configure.py --bootstrap
 Then add ~/ninja/ to your PATH.
 EOF