grains: workaround transpiler error (#304)

* grains: workaround transpiler error

* Update abaplint.json

abaplint.json

@@ -697,7 +697,7 @@
       "severity": "Error"
     },
     "prefer_inline": {
-      "exclude": [],
+      "exclude": ["grains"],
       "severity": "Error"
     },
     "prefer_is_not": {

exercises/practice/grains/zcl_grains.clas.testclasses.abap

@@ -103,9 +103,11 @@ CLASS ltcl_grains IMPLEMENTATION.
 
   "returns the total number of grains on the board
   METHOD test_total.
+    DATA lv_expected TYPE zcl_grains=>type_result.
+    lv_expected = 18446744073709551615.
     cl_abap_unit_assert=>assert_equals(
       act = cut->total( )
-      exp = 18446744073709551615 ).
+      exp = lv_expected ).
   ENDMETHOD.