treewide: disable pie in more places

Some packages don’t work correctly with pie. Here I disable it for:

- busybox
- linux kernel
- kexectools

I also get rid of the Musl conditional for disabling pie in GCC and
Binutils. Some day we might want to enable PIE without Musl and it
will be useful to have the *just* work with our compiler and linkers.

pkgs/development/tools/misc/binutils/default.nix

@@ -97,7 +97,7 @@ stdenv.mkDerivation rec {
     then "-Wno-string-plus-int -Wno-deprecated-declarations"
     else "-static-libgcc";
 
-  hardeningDisable = [ "format" ] ++ stdenv.lib.optional stdenv.targetPlatform.isMusl "pie";
+  hardeningDisable = [ "format" "pie" ];
 
   # TODO(@Ericson2314): Always pass "--target" and always targetPrefix.
   configurePlatforms = [ "build" "host" ] ++ stdenv.lib.optional (stdenv.targetPlatform != stdenv.hostPlatform) "target";