Suppress UBSAN warning in CRC32 ARM (#6827)

Summary:
UBSAN shows following warning:

util/crc32c_arm64.cc:111:11: runtime error: load of misaligned address 0x00001afcda86 for type 'const uint64_t', which requires 8 byte alignment
0x00001afcda86: note: pointer points here
cc c1 2d 00 01 81  40 24 30 66 39 66 30 37  30 63 2d 32 36 63 34 2d  34 62 61 61 2d 38 35 33  31 2d
^

Suppress it just as what we do in x86 CRC.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6827

Test Plan: Run the same UBSAN and see it to pass now.

Reviewed By: ltamasi

Differential Revision: D21471838

fbshipit-source-id: 02943dd39a7030d2b03e5d894dcb23ed72b6c9c3

util/crc32c_arm64.cc

@@ -44,6 +44,13 @@ uint32_t crc32c_runtime_check(void) {
 #endif
 }
 
+#ifdef ROCKSDB_UBSAN_RUN
+#if defined(__clang__)
+__attribute__((__no_sanitize__("alignment")))
+#elif defined(__GNUC__)
+__attribute__((__no_sanitize_undefined__))
+#endif
+#endif
 uint32_t crc32c_arm64(uint32_t crc, unsigned char const *data,
                              unsigned len) {
   const uint8_t *buf8;