uint256: Remove unnecessary crypto/common.h use

src/hash.h

@@ -6,6 +6,7 @@
 #ifndef BITCOIN_HASH_H
 #define BITCOIN_HASH_H
 
+#include <crypto/common.h>
 #include <crypto/ripemd160.h>
 #include <crypto/sha256.h>
 #include <prevector.h>
@@ -138,6 +139,15 @@ public:
         return result;
     }
 
+    /**
+     * Returns the first 64 bits from the resulting hash.
+     */
+    inline uint64_t GetCheapHash() {
+        unsigned char result[CHash256::OUTPUT_SIZE];
+        ctx.Finalize(result);
+        return ReadLE64(result);
+    }
+
     template<typename T>
     CHashWriter& operator<<(const T& obj) {
         // Serialize to this stream