Un-ignore "vmlinux.lds.S" in .gitignore

We ignore all the generated files called "vmlinux*" from the top-level
gitignore, but that also ends up catching a few files that we track, and
that people do edit. Notably the "vmlinux.lds.S" file, that each
architecture has.

You can always use "git add -f" to override the ignore file, but we
might as well just make it explicit for this file.

Bitten-by-and-tested-by: Ingo Molnar <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

.gitignore

···
 tags
 TAGS
 vmlinux*
+!vmlinux.lds.S
 System.map
 Module.symvers