Add .swp files to gitignore.

Make git ignore .swp files (generated while editing in vim).

Review URL: https://codereview.appspot.com/7309059

git-svn-id: http://skia.googlecode.com/svn/trunk@7669 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/.gitignore b/.gitignore
index 237b7f1..1ef10dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+*.swp
 .android_config
 .DS_Store
 .gclient*