fix: riscv64 build error

source/time/timestamp.cpp

@@ -284,7 +284,7 @@ uint64_t Timestamp::rdts()
     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(__loongarch__) || defined(__riscv) 
     // mips apparently only allows rdtsc for superusers, so we fall back to gettimeofday.
     // It's possible clock_gettime would be better.
     struct timeval tv;