cannot run test_throw in test_rpython along with other pytests
(especially tests from c script). Will look into this later

other tests

going to test it with test_jit suite

NOTE: Only fixed hand-written ASMs. Emitted ".s" files still have problems.

internal id and machine id do not persist during serialization
and restoration. Currently I use fixed ID for machine registers.
But internal id is still generated, this might be a problem in
the future.

gonna implement THREADEXIT