Add a 2 width option of clang format.

Make the default the 4 tab space version.

Add a link to the 2 space version for libbacktrace.

The only other difference between the 4 space and 2 space tab version
is that the 2 space tab version allows short functions on a single line.
This is for things like constructors, short destructors, or accessor
functions. I believe this is closer to the Google C++ style guide.

Bug: 36046320

Test: NA
Change-Id: Ida08db18902eeb101f42869dd5590182529d54ef
diff --git a/.clang-format-2 b/.clang-format-2
new file mode 100644
index 0000000..fb967d8
--- /dev/null
+++ b/.clang-format-2
@@ -0,0 +1,13 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: false
+AllowShortFunctionsOnASingleLine: true
+
+AccessModifierOffset: -1
+ColumnLimit: 100
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+IndentWidth: 2
+PointerAlignment: Left
+TabWidth: 2
+UseTab: Never
+PenaltyExcessCharacter: 32