Avoid integer sanitizer warnings in chain.o

src/chain.cpp

@@ -151,7 +151,7 @@ int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& fr
     if (r.bits() > 63) {
         return sign * std::numeric_limits<int64_t>::max();
     }
-    return sign * r.GetLow64();
+    return sign * int64_t(r.GetLow64());
 }
 
 /** Find the last common ancestor two blocks have.