RFR(S): fix System.arraycopy() C2 intrinsics with arrays of value types

[Roland Westrelin]

Hi Tobias,

> TestArrays.java:
> - Should we add -XX:-ReduceInitialCardMarks to one of the runs?

Are you suggesting we add an extra @run command to the test (duplicating
the first one?) with the extra -XX:-ReduceInitialCardMarks?

Roland.