Increase refund counter if deleting a storage item [Delivers #81575908]

evmcc/test/ext/store_delete.evm

@@ -0,0 +1 @@
+6104d26063576000606357

evmcc/test/ext/store_delete.lll

@@ -0,0 +1,9 @@
+
+(asm 
+1234
+99
+SSTORE
+0
+99
+SSTORE
+)

libevmjit/Ext.cpp

@@ -6,6 +6,7 @@
 #include <llvm/IR/IntrinsicInst.h>
 
 #include <libdevcrypto/SHA3.h>
+#include <libevm/FeeStructure.h>
 
 #include "Runtime.h"
 #include "Type.h"
@@ -179,7 +180,12 @@ extern "C"
 	{
 		auto index = llvm2eth(*_index);
 		auto value = llvm2eth(*_value);
-		_rt->getExt().setStore(index, value); // Interface uses native endianness
+		auto& ext = _rt->getExt();
+
+		if (value == 0 && ext.store(index) != 0)	// If delete
+			ext.sub.refunds += c_sstoreRefundGas;	// Increase refund counter
+
+		ext.setStore(index, value);	// Interface uses native endianness
 	}
 
 	EXPORT void ext_calldataload(Runtime* _rt, i256* _index, i256* _value)