Normalize build files using Bazel's build file formatter (buildifier).

Created by: bolinfest

I created a small fork of https://github.com/bazelbuild/buildifier at https://github.com/bolinfest/buildifier/tree/buck. The notable changes are:

• Use single quotes instead of double quotes.
• Use 2-space indents instead of 4-space indents.

I built my fork as per the instructions:

bazel build //buildifier

I copied the output to my local Buck repo:

cp ~/code/buildifier/bazel-bin/buildifier/buildifier buildifier

And then I ran it on Buck itself:

./buildifier -showlog -mode=fix -buildifier_disable=label $(find . -name BUCK -type f)

The results of running buildifier can be seen in this commit.

Note that it emitted two warnings when I ran it:

./test/com/facebook/buck/apple/BUCK:1:28: syntax error near :
./src/com/facebook/buck/apple/BUCK:1:28: syntax error near :

I believe this has to do with our unconventional use of with in those build files:

with allow_unsafe_import():
    from sys import platform as os_platform