RFR(S): 8202747: C2: assert(mode == ControlAroundStripMined && use == sfpt) failed: missed a node

[Roland Westrelin]

http://cr.openjdk.java.net/~roland/8202747/webrev.00/

When cloning a strip mined loop nest, verification code catches a data
node that's not referenced from the safepoint node but is found to be in
the outer loop. That's caused by another transformation in the same
round of loop opts that pessimistically assigned control in the outer
loop to the data node. The fix I propose is to locate those nodes that
shouldn't be in the outer loop and fix their control during loop
cloning.

Roland.