arm/tcg-test: some basic TCG exercising tests

These tests are not really aimed at KVM at all but exist to stretch
QEMU's TCG code generator. In particular these exercise the ability of
the TCG to:

  * Chain TranslationBlocks together (tight)
  * Handle heavy usage of the tb_jump_cache (paged)
  * Pathological case of computed local jumps (computed)

In addition the tests can be varied by adding IPI IRQs or SMC sequences
into the mix to stress the tcg_exit and invalidation mechanisms.

To explicitly stress the tb_flush() mechanism you can use the mod/rounds
parameters to force more frequent tb invalidation. Combined with setting
-tb-size 1 in QEMU to limit the code generation buffer size.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20211202115352.951548-10-alex.bennee@linaro.org>
Signed-off-by: Andrew Jones <drjones@redhat.com>