[PATCH] Added transform for ABS(NABS(X)) and NABS(ABS(X))

[Dinesh Dwivedi]

Thanks,

I had submitted similar patch [http://reviews.llvm.org/D3658] with all permutations of icmp.
This was just followup patch.

I am submitting it as it is. But if you care, I can remove few test cases for both changes.
In that case, we may not to add new file [abs_abs.ll], which I have added just because
there were too many test cases to add.

http://reviews.llvm.org/D4040