Rollup merge of rust-lang#52615 - davidtwco:add-to-gitignore, r=nikomatsakis,Mark-Simulacrum

Added new lines to .gitignore.

There are a handful of files that I often find in my local working directories that I never want to commit that aren't covered in the `.gitignore` file:

`/mir_dump`:
Default output location from `-Z mir-dump=all` for a specific test, I can't think of a reason why this should ever be commited.

`tags*`/`TAGS*`:
I use `vim-gutentags` which outputs `tags` and `tags.temp` which I don't want commited. I also collapsed the `TAGS`, `TAGS.vi`, `TAGS.emacs` into `TAGS*`.

`Session.vim`:
I use `vim-obsession` to save my current session in Vim, it outputs a `Session.vim` file, this also shouldn't be commited.

Author: kennytm

.gitignore

@@ -86,15 +86,18 @@ __pycache__/
 target/
 /test/
 /tmp/
+tags
+tags.*
 TAGS
-TAGS.emacs
-TAGS.vi
+TAGS.*
 \#*
 \#*\#
 config.mk
 config.stamp
 keywords.md
 lexer.ml
+mir_dump
+Session.vim
 src/etc/dl
 tmp.*.rs
 version.md