Since legacy binding for loop unswitch pass was removed and we can't get it back. Implement its equivalent in `aot_llvm_extra.cpp` and use it in `aot_compiler.c`. Follow up to #1183.
Since legacy binding for loop unswitch pass was removed and we can't get it back. Implement its equivalent in `aot_llvm_extra.cpp` and use it in `aot_compiler.c`. Follow up to #1183.