treewide: cleanup some references to bash

pkgs/build-support/cc-wrapper/default.nix

@@ -75,7 +75,7 @@ stdenv.mkDerivation {
   preferLocalBuild = true;
 
   inherit cc libc_bin libc_dev libc_lib bintools coreutils_bin;
-  shell = getBin shell + stdenv.lib.optionalString (stdenv ? shellPath) stdenv.shellPath;
+  shell = getBin shell + shell.shellPath or "";
   gnugrep_bin = if nativeTools then "" else gnugrep;
 
   inherit targetPrefix infixSalt;

pkgs/top-level/all-packages.nix

@@ -6222,7 +6222,7 @@ with pkgs;
 
   ### SHELLS
 
-  runtimeShell = "${runtimeShellPackage}/bin/bash";
+  runtimeShell = "${runtimeShellPackage}${runtimeShellPackage.shellPath}";
   runtimeShellPackage = bash;
 
   bash = lowPrio (callPackage ../shells/bash/4.4.nix { });