swift: update for cc-wrapper changes

The Swift compiler derivation modifies the clang wrapper to use
`exec -a "$0"` to allow it to use the same binary for both `clang` and
`clang++`. The sed script it uses to do this fails after the cc-wrapper
changes in 6f2b3ba027 were merged.

This is fixed by updating `makeClangWrapper` to work with the cc-wrapper
changes by having Bash invoke a simple script that uses `exec -a "$0"`
to set the required name for clang.

This fixes the staging-next build failures with Swift on Darwin and Linux.

https://github.com/NixOS/nixpkgs/pull/248496#issuecomment-1676831102

pkgs/development/compilers/swift/compiler/default.nix

@@ -2,6 +2,7 @@
 , stdenv
 , callPackage
 , cmake
+, bash
 , coreutils
 , gnugrep
 , perl
@@ -133,7 +134,8 @@ let
     sed < '${clang}/bin/clang' > "$targetFile" \
       -e 's|^\s*exec|exec -a "$0"|g' \
       -e 's|^\[\[ "${clang.cc}/bin/clang" = \*++ ]]|[[ "$0" = *++ ]]|' \
-      -e "s|${clang.cc}/bin/clang|$unwrappedClang|g"
+      -e "s|${clang.cc}/bin/clang|$unwrappedClang|g" \
+      -e "s|^\(\s*\)\($unwrappedClang\) \"@\\\$responseFile\"|\1argv0=\$0\n\1${bash}/bin/bash -c \"exec -a '\$argv0' \2 '@\$responseFile'\"|"
     chmod a+x "$targetFile"
   '';