tar: fix build with automake 1.12.x

tar: fix build with automake 1.12.x

automake 1.12.x automatically deletes empty directories, so
the additional rmdir from the do_install_append fails.

cleanup the do_install_append for automake 1.12.x

Avoid this error:
| rmdir: failed to remove `/srv/home/nitin/builds/build-gcc47/tmp/work/i586-poky-linux/tar-1.26-r1/image/usr/sbin/': No such file or directory
NOTE: package tar-1.26-r1: task do_install: Failed

no PR bump as no change in the output.

(From OE-Core rev: c3c103abb533cc9aae178d41b1bd216165f3bc9a)

Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>