gitignore: Add build folder to gitgnore

This folder is created by running ./setup.py build

Change-Id: Iaf0a1b825b5172aa18d021ed858cbbc42eede883
diff --git a/.gitignore b/.gitignore
index f781d3d..14ca2c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 virtualenv
 out/
+build
 __pycache__
 blueberry/*
 !blueberry/__init__.py
-.eggs/
\ No newline at end of file
+.eggs/