Optimize CRC32 for Ampere Siryn

Siryn's crc32 instruction seems to have latency 3 and throughput 1, which makes the optimal ratio of pmull and crc streams close to that of tested x86 machines. Up to +120% faster for large inputs.

PiperOrigin-RevId: 568645559
Change-Id: I86b85b1b2a5d4fb3680c516c4c9044238b20fe61

absl/crc/internal/crc_x86_arm_combined.cc

@@ -636,6 +636,9 @@ CRCImpl* TryNewCRC32AcceleratedX86ARMCombined() {
     case CpuType::kArmNeoverseN1:
       return new CRC32AcceleratedX86ARMCombinedMultipleStreams<
           1, 1, CutoffStrategy::Unroll64CRC>();
+    case CpuType::kAmpereSiryn:
+      return new CRC32AcceleratedX86ARMCombinedMultipleStreams<
+          3, 2, CutoffStrategy::Fold3>();
 #if defined(__aarch64__)
     default:
       // Not all ARM processors support the needed instructions, so check here