Fix testgrounds build

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>

build/params_testground.go

@@ -66,4 +66,7 @@ var (
 	// Actor consts
 	// TODO: Pull from actors when its made not private
 	MinDealDuration = abi.ChainEpoch(180 * builtin.EpochsInDay)
+
+	PackingEfficiencyNum   int64 = 4
+	PackingEfficiencyDenom int64 = 5
 )

chain/store/basefee.go

@@ -17,7 +17,7 @@ func computeNextBaseFee(baseFee types.BigInt, gasLimitUsed int64, noOfBlocks int
 	// nextBaseFee = baseFee + change
 	// nextBaseFee = max(nextBaseFee, build.MinimumBaseFee)
 
-	delta := build.PackingEfficiencyDenom * gasLimitUsed / int64(noOfBlocks*build.PackingEfficiencyNum)
+	delta := build.PackingEfficiencyDenom * gasLimitUsed / (int64(noOfBlocks) * build.PackingEfficiencyNum)
 	delta -= build.BlockGasTarget
 
 	// cap change at 12.5% (BaseFeeMaxChangeDenom) by capping delta