We'll rely on the toolchain probing to determine whether each arch's
tests can be run rather the current configure target. This allows
testing all of the ports in a multitarget configuration.
For now, we don't reformat the files entirely to make it easier to
review, and in case we need to make adjustments. Once this feels
like it's stable, we can flatten the code a bit by removing the if
statement entirely.
Now that all port tests live under testsuite/sim/*/, and none live
in testsuite/ directly, flatten the structure by moving all of the
dirs under testsuite/sim/ to testsuite/ directly.
We need to stop passing --tool to dejagnu so that it searches all
dirs and not just ones that start with "sim". Since we have no
other dirs in this tree, and no plans to add any, should be fine.
