Modified block of letstmt simplification to allow different names.
Modified block of letstmt simplification to allow different names.


Former-commit-id: 7f1b5d86f534eaca1909d55591d5a578750d70a7
darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide