RFR (L): 7173584: Implement arraycopy as a macro node

[Roland Westrelin]

Here is a new one for this (ignore the comments below the file names. They are broken):

http://cr.openjdk.java.net/~roland/7173584/webrev.01/

The 2 changes are:

- the fix for 7174363 is merged
- I hit an assert once during testing:
assert(proj->_con == predicate_proj->_con, "must match");
loopPredicate.cpp line 825
One of the predicates added for an array copy is mistaken for a range check predicate but with the IfTrue/IfFalse projections swapped so I tried to change the code so that proj->_con != predicate_proj->_con is supported.

Roland.