[llvm] [DA] remove constraint propagation (PR #160924)

[Ehsan Amiri via llvm-commits]

amehsan wrote:

> Constraint propagation is important to speed up dependence test and transform MIV tests into easier SIV and ZIV tests.
> Those interested in details, please read the paper mentioned in the header of DA.cpp: https://softlib.rice.edu/pub/CRPC-TRs/reports/CRPC-TR90103-S.pdf

IIRC Table 2 has a statistics on how often these tests are applied in the experiments. 

https://github.com/llvm/llvm-project/pull/160924