Rollup merge of rust-lang#83001 - camelid:gitignore-vim-swap, r=Mark-Simulacrum

Ignore Vim swap files

I got this from [a Stack Overflow answer][so].
(I didn't add `*~` because it was already there.)

[so]: https://stackoverflow.com/a/4824199

Author: JohnTitor

.gitignore

@@ -7,6 +7,8 @@
 # configure your local ignore list.
 # FIXME: This needs cleanup.
 *~
+*.swp
+*.swo
 .#*
 .DS_Store
 .cproject