Avoid position sensitive argument errors with tar

Running art/tools/golem/build-target.sh with a more recent GNU tar
yields errors relating to --exclude being position sensitive
arguments. Move to latterly expected positions.

Test: art/tools/golem/build-target --machine-type=linux-armv7 --golem=art-opt-cc --tarball
Change-Id: I6d4d4bb3f52a8b76960813679be200e8337d3b21