Add .clang-format style file.

The file is forked from bionic project. It's mostly in Google style, with
some tweaks (e.g. 100 column limit). New CLs can be formatted with `git
clang-format --style=file`.

Test: N/A
Change-Id: I6fbd0ab851c03aa6de9987777c7da8cdca8964ed
diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..b8c6428
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,14 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+ColumnLimit: 100
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+IndentWidth: 2
+PointerAlignment: Left
+TabWidth: 2
+UseTab: Never
+PenaltyExcessCharacter: 32
+Cpp11BracedListStyle: false