RFR(L): 6912521: System.arraycopy works slower than the simple loop for little lengths

[Roland Westrelin]

One of the changes I made following reviews introduced a bug that triggered when I tried to push this through jprt. I also realized that if the copy length is 1 there’s no need to check for overlapping copies. So I intend to push webrev.01 plus this:

http://cr.openjdk.java.net/~roland/6912521/webrev.02/

Roland.