test: Properly clear storage dirty flag

Clear storage dirty flag between transactions in EVMHost. The EIP-2200
dirty flag should be persisted only in a single transaction.

test/libsolidity/semanticTests/structs/copy_struct_array_from_storage.sol

@@ -87,9 +87,9 @@ contract Test {
 // EVMVersion: >homestead
 // ----
 // test1() -> true
-// gas irOptimized: 150163
-// gas legacy: 150266
-// gas legacyOptimized: 149875
+// gas irOptimized: 152963
+// gas legacy: 153066
+// gas legacyOptimized: 152675
 // test2() -> true
 // test3() -> true
 // test4() -> true

test/libsolidity/semanticTests/structs/struct_containing_bytes_copy_and_delete.sol

@@ -31,6 +31,9 @@ contract c {
 // copy() -> true
 // storageEmpty -> 1
 // set(uint256,bytes,uint256): 12, 0x60, 13, 33, "12345678901234567890123456789012", "3" -> true
+// gas irOptimized: 133599
+// gas legacy: 134654
+// gas legacyOptimized: 133882
 // storageEmpty -> 0
 // del() -> true
 // storageEmpty -> 1

test/libsolidity/semanticTests/structs/struct_delete_storage_with_array.sol

@@ -46,3 +46,6 @@ contract C {
 // gas legacy: 122132
 // gas legacyOptimized: 121500
 // g() ->
+// gas irOptimized: 145472
+// gas legacy: 145707
+// gas legacyOptimized: 144940