RandomX fixes

- Fixed possible infinite loop when updating RandomX dataset
- Fixed used memory display
- Allocate dataset and VM for RandomX only when it's actually used

src/workers/MultiWorker.h

@@ -49,6 +49,8 @@ protected:
     void start() override;
 
 private:
+    void allocateRandomX_VM();
+
     bool resume(const xmrig::Job &job);
     bool verify(xmrig::Variant variant, const uint8_t *referenceValue);
     bool verify2(xmrig::Variant variant, const uint8_t *referenceValue);