Add .clang-format symlink to Brillo's clang-format.

Bug: 27121653
TEST=Ran clang-format.

Change-Id: I0dd8b8fcdcc2a8422d9cc0c28bd0225310e048a6
diff --git a/.clang-format b/.clang-format
new file mode 120000
index 0000000..f412743
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1 @@
+../../build/tools/brillo-clang-format
\ No newline at end of file