Rollup merge of #77624 - akoptelov:c-all-targets-fix, r=jyn514

Add c as a shorthand check alternative for new options #77603

There is a missing "c" that is a shorthand for "check" in newly added match arm for handling check-specific options.

src/bootstrap/flags.rs

@@ -254,7 +254,7 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`",
                         `/<build_base>/rustfix_missing_coverage.txt`",
                 );
             }
-            "check" => {
+            "check" | "c" => {
                 opts.optflag("", "all-targets", "Check all targets");
             }
             "bench" => {