Added a pruning mutator to the specialize branched loops code that can be applied after normalizing if stmts to cut down on the number of branches that need to be considered.
Added a pruning mutator to the specialize branched loops code that can be applied after normalizing if stmts to cut down on the number of branches that need to be considered.


Former-commit-id: c7617700f6086c0253cf645647a06d6b3ca7a405
Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide