Ignore nameless vim swap files
Ignore nameless vim swap files

Starting vim with no file name creates a swap file in the form of .swp,
.swo etc.  Add these files to .gitignore.

Bug: None
Change-Id: Id9639f626daebc993ccc9ab0a9049a18e0f80862
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1975612
Reviewed-by: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Commit-Queue: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle