Remove nix-portable tmpbin feature

It will not work without the host /lib64/ld

Reviewed-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>

pkgs/nix-portable/default.nix

@@ -179,10 +179,6 @@ let
     store="\$dir/nix/store"
     # create /nix/var/nix to prevent nix from falling back to chroot store.
     mkdir -p \$dir/{bin,nix/var/nix,nix/store}
-    # sanitize the tmpbin directory
-    rm -rf "\$dir/tmpbin"
-    # create a directory to hold executable symlinks for overriding
-    mkdir -p "\$dir/tmpbin"
 
     # create minimal drv file for nix to spawn a nix shell
     echo 'builtins.derivation {name="foo"; builder="/bin/sh"; args = ["-c" "echo hello \> \\\$out"]; system=builtins.currentSystem;}' > "\$dir/mini-drv.nix"
@@ -575,11 +571,6 @@ let
     ### set PATH
     # restore original PATH and append busybox
     export PATH="\$PATH_OLD:\$dir/busybox/bin"
-    # apply overriding executable paths in \$dir/tmpbin/
-    export PATH="\$dir/tmpbin:\$PATH"
-
-
-
 
     ### install programs via nix
     ${concatMapStringsSep "\n" installDynamic bootstrapPrograms}