[testsuite][M680x0] Add CycleTimer implementation for M68K architecture

[myhsu]

Summary

This is a cherrypick of the upstream fix commit ffe1342 onto the google benchmark within llvm-test-suite.
This adds CycleTimer implementation for M680x0, and simply uses gettimeofday to implement, same as MIPS.

[lebedev.ri]

LG, thank you.

[myhsu]

https://github.com/llvm/llvm-test-suite/commit/25883edc2f615a84c4fa741e997904293474bbc0

MicroBenchmarks/libs/benchmark-1.3.0/AUTHORS

 Oleksandr Sochka <[e-mail]>
 Paul Redmond <[e-mail]>
 Radoslav Yovchev <[e-mail]>
 Roman Lebedev <[e-mail]>
 Shuo Chen <[e-mail]>
 Yixuan Qiu <[e-mail]>
 Yusuke Suzuki <[e-mail]>
 Zbigniew Skowron <[e-mail]>
+Min-Yih Hsu <[e-mail]>

MicroBenchmarks/libs/benchmark-1.3.0/CONTRIBUTORS

 Ray Glover <[e-mail]>
 Roman Lebedev <[e-mail]>
 Shuo Chen <[e-mail]>
 Tobias Ulvgård <[e-mail]>
 Tom Madams <[e-mail]> <[e-mail]>
 Yixuan Qiu <[e-mail]>
 Yusuke Suzuki <[e-mail]>
 Zbigniew Skowron <[e-mail]>
+Min-Yih Hsu <[e-mail]>

MicroBenchmarks/libs/benchmark-1.3.0/README.llvm

 * https://github.com/google/benchmark/commit/4abdfbb802d1b514703223f5f852ce4a507d32d2
   is applied on top of v1.3.0 to add RISC-V timer support.
 * https://github.com/google/benchmark/commit/a77d5f70efaebe2b7e8c10134526a23a7ce7ef35
   and
   https://github.com/google/benchmark/commit/ecc1685340f58f7fe6b707036bc0bb1fccabb0c1
   are applied on top of v1.3.0 to fix timestamp-related inline asm issues and
   32-bit RISC-V build failures. The second cherrypicked commit fixes formatting
   issues introduced by the first one.
+* https://github.com/google/benchmark/commit/ffe1342eb2faa7d2e7c35b4db2ccf99fab81ec20
+  is applited on top of v1.3.0 to add the CycleTimer implementation for M680x0

MicroBenchmarks/libs/benchmark-1.3.0/src/cycleclock.h

if (pmcntenset & 0x80000000ul) {  // Is it counting?
       // The counter is set up to count every 64th cycle
       return static_cast<int64_t>(pmccntr) * 64;  // Should optimize to << 6
     }
   }
 #endif
   struct timeval tv;
   gettimeofday(&tv, nullptr);
   return static_cast<int64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
-#elif defined(__mips__)
+#elif defined(__mips__) || defined(__m68k__)
   // mips apparently only allows rdtsc for superusers, so we fall
   // back to gettimeofday.  It's possible clock_gettime would be better.
   struct timeval tv;
   gettimeofday(&tv, nullptr);
   return static_cast<int64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
 #elif defined(__s390__) // Covers both s390 and s390x.
   // Return the CPU clock.
   uint64_t tsc;