Introduce FastRandomContext::randbool()

Author: sipa

src/random.h

@@ -42,6 +42,10 @@ class FastRandomContext {
         return (Rw << 16) + Rz;
     }
 
+    bool randbool() {
+        return rand32() & 1;
+    }
+
     uint32_t Rz;
     uint32_t Rw;
 };

src/wallet/wallet.cpp

@@ -2048,7 +2048,7 @@ static void ApproximateBestSubset(const std::vector<std::pair<CAmount, std::pair
                 //that the rng is fast. We do not use a constant random sequence,
                 //because there may be some privacy improvement by making
                 //the selection random.
-                if (nPass == 0 ? insecure_rand.rand32()&1 : !vfIncluded[i])
+                if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i])
                 {
                     nTotal += vValue[i].first;
                     vfIncluded[i] = true;