[tests] Add specifier of implicit ints in tests

tests/value/const.i

tests/value/constarraystructlibentry.i

tests/value/conversion.i

tests/value/dataflow_order.i

tests/value/degeneration2.i

tests/value/deps_unitialized_locals.i

tests/value/downcast.i

tests/value/gauges.c

tests/value/if2.i

tests/value/init_const_guard.i

tests/value/initialized.c

tests/value/library.i

tests/value/local_slevel.i

tests/value/logic.c

tests/value/modulo.i

tests/value/non_natural.i

tests/value/overflow_cast_float_int.i

tests/value/partitioning-annots.c

tests/value/reduce_by_valid.i

tests/value/shift.i