This change simply moves the `rust` macro definition directly into the
attributes for `*.rs` files.
git commands that recurse from the rust toplevel tree into submodules
produce errors in clippy due to the fact that:
"Custom macro attributes can be defined only in top-level
gitattributes files"
For example, from the toplevel `rust` directory in a rustc development
build, try:
$ git grep "search string" --recurse-submodules
Embedded within the actual results is the error message:
[attr]rust text eol=lf whitespace=tab-in-indent,trailing-space,tabwidth=4
not allowed: src/tools/clippy/.gitattributes:1
-[attr]rust text eol=lf whitespace=tab-in-indent,trailing-space,tabwidth=4
-
* text=auto eol=lf
-*.rs rust
+*.rs text eol=lf whitespace=tab-in-indent,trailing-space,tabwidth=4
*.fixed linguist-language=Rust