AstroBWT algorithm (DERO) support

To test:

- Download https://github.com/deroproject/derosuite/releases/tag/AstroBWT
- Run daemon with `--testnet` in command line

In config.json:
- "coin":"dero"
- "url":"127.0.0.1:30306"
- "daemon:"true"

src/backend/cpu/platform/BasicCpuInfo.cpp

@@ -258,5 +258,15 @@ xmrig::CpuThreads xmrig::BasicCpuInfo::threads(const Algorithm &algorithm, uint3
     }
 #   endif
 
+#   ifdef XMRIG_ALGO_ASTROBWT
+    if (algorithm.family() == Algorithm::ASTROBWT) {
+        CpuThreads threads;
+        for (size_t i = 0; i < count; ++i) {
+            threads.add(i, 0);
+        }
+        return threads;
+    }
+#   endif
+
     return CpuThreads(std::max<size_t>(count / 2, 1), 1);
 }