Rollup merge of #82163 - matthiaskrgr:slice, r=jyn514

avoid full-slicing slices

If we already have a slice, there is no need to get another full-range slice from that, just use the original.
clippy::redundant_slicing

src/bootstrap/flags.rs

@@ -347,7 +347,7 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`",
         };
 
         // Done specifying what options are possible, so do the getopts parsing
-        let matches = opts.parse(&args[..]).unwrap_or_else(|e| {
+        let matches = opts.parse(args).unwrap_or_else(|e| {
             // Invalid argument/option format
             println!("\n{}\n", e);
             usage(1, &opts, false, &subcommand_help);