This reverts https://reviews.llvm.org/D120329.
I abandoned the PR [0] to add __divei4 functions to compiler-rt
in favor of adding a pass to transform div/rem [1].
This removes the backend code that was supposed to emit calls to the __divei4 functions.
[0] https://reviews.llvm.org/D120327
[1] https://reviews.llvm.org/D130076