[16] RFR (S) 8249749: modify a primitive array through a stream and a for cycle causes jre crash

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8249749/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8249749

SuperWord does not recognize array indexing pattern used in the test due to additional AddI node:

AddI(AddI(Invariant(j*n), Loop_phi(i)), Loop_inc(1))

As result it can't find memory reference to align vectors. But code ignores that and continue execution.
Later when align_to_ref is referenced we hit SEGV because it is NULL.

The fix is to check align_to_ref for NULL early and bailout.

I also adjusted code in SWPointer::scaled_iv_plus_offset() to recognize this address pattern to vectorize test's code.
And added missing _invar setting.

And I slightly modified tracking code to investigate this issue.

Added new test to check some complex address expressions similar to bug's test case. Not all cases in test are 
vectorized - there are other conditions which prevent that.

Tested tier1,tier2,hs-tier3,precheckin-comp

Thanks,
Vladimir K