The tests under tests/tcg depend on the TCG accelerator. Do not build
them if --disable-tcg was given in the configure line.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230120184825.31626-7-farosas@suse.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>