test: remove fSkipProofOfWork

Not used, and REGTEST already allows creating blocks at
the lowerst possible difficulty.

src/chainparams.cpp

@@ -170,7 +170,6 @@ public:
         fAllowMinDifficultyBlocks = false;
         fRequireStandard = true;
         fMineBlocksOnDemand = false;
-        fSkipProofOfWorkCheck = false;
         fTestnetToBeDeprecatedFieldRPC = false;
     }
 

src/chainparams.h

@@ -60,8 +60,6 @@ public:
     bool DefaultCheckMemPool() const { return fDefaultCheckMemPool; }
     /** Allow mining of a min-difficulty block */
     bool AllowMinDifficultyBlocks() const { return fAllowMinDifficultyBlocks; }
-    /** Skip proof-of-work check: allow mining of any difficulty block */
-    bool SkipProofOfWorkCheck() const { return fSkipProofOfWorkCheck; }
     /** Make standard checks */
     bool RequireStandard() const { return fRequireStandard; }
     int64_t TargetTimespan() const { return nTargetTimespan; }
@@ -104,7 +102,6 @@ protected:
     bool fAllowMinDifficultyBlocks;
     bool fRequireStandard;
     bool fMineBlocksOnDemand;
-    bool fSkipProofOfWorkCheck;
     bool fTestnetToBeDeprecatedFieldRPC;
 };
 

src/main.cpp

@@ -2593,8 +2593,7 @@ bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& sta
     int nHeight = pindexPrev->nHeight+1;
 
     // Check proof of work
-    if ((!Params().SkipProofOfWorkCheck()) &&
+    if ((block.nBits != GetNextWorkRequired(pindexPrev, &block)))
-       (block.nBits != GetNextWorkRequired(pindexPrev, &block)))
         return state.DoS(100, error("%s: incorrect proof of work", __func__),
                          REJECT_INVALID, "bad-diffbits");
 

src/pow.cpp

@@ -87,9 +87,6 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits)
     bool fOverflow;
     arith_uint256 bnTarget;
 
-    if (Params().SkipProofOfWorkCheck())
-       return true;
-
     bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
 
     // Check range