target-arm: Add support for AArch32 ARMv8 CRC32 instructions

target-arm: Add support for AArch32 ARMv8 CRC32 instructions

Add support for AArch32 CRC32 and CRC32C instructions added in ARMv8
and add a CPU feature flag to enable these instructions.

The CRC32-C implementation used is the built-in qemu implementation
and The CRC-32 implementation is from zlib. This requires adding zlib
to LIBS to ensure it is linked for the linux-user binary.

Signed-off-by: Will Newton <[email protected]>
Reviewed-by: Peter Maydell <[email protected]>
Message-id: 1393411566[email protected]
Signed-off-by: Peter Maydell <[email protected]>