This converts the existing Makefile into a Makefile.target and updates
it so it can be called by the tcg build system. The original Makefile
didn't set -cpu except for the v17 tests however that has broken (I
assume because linux-user is a "max" cpu) so here I force it to be
crisv17.
I've also replicated the GNU simulator targets (run-FOO-on-sim).
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
