gitignore vim swp files

Change-Id: I2d60ad2365c7fd82210ee1dac96fabab19617280
diff --git a/.gitignore b/.gitignore
index bf5baa0..8282f5f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,4 @@
 */Makefile
 !bin/Makefile
 !deps/Makefile
+.*.sw?