target/arm: Inform helpers whether a PAC instruction is 'combined'

target/arm: Inform helpers whether a PAC instruction is 'combined'

An instruction is a 'combined' Pointer Authentication instruction
if it does something in addition to PAC -- for instance, branching
to or loading an address from the authenticated pointer.

Knowing whether a PAC operation is 'combined' is needed to
implement FEAT_FPACCOMBINE.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Aaron Lindsay <aaron@os.amperecomputing.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230829232335.965414-9-richard.henderson@linaro.org
Message-Id: <20230609172324.982888-7-aaron@os.amperecomputing.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>