add .gitignore

Change-Id: Ifabe7e961f57d07168baa71d197490e55bf7b12d
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c795b05
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+build
\ No newline at end of file