tests/tcg/aarch64: Adjust pauth tests for FEAT_FPAC

tests/tcg/aarch64: Adjust pauth tests for FEAT_FPAC

With FEAT_FPAC, AUT* instructions that fail authentication
do not produce an error value but instead fault.

For pauth-2, install a signal handler and verify it gets called.

For pauth-4 and pauth-5, we are explicitly testing the error value,
so there's nothing to test with FEAT_FPAC, so exit early.
Adjust the makefile to use -cpu neoverse-v1, which has FEAT_EPAC
but not FEAT_FPAC.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230829232335.965414-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>