Now we have a nios2 test image we can start using it to build tests.
However signal handling in nios2 is still broken so we disable the
signals and linux-test tests that trigger the bug.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211026102234.3961636-12-alex.bennee@linaro.org>