[InstCombine] refactor sdiv by APInt transforms (NFC)

There's at least one more fold to do here:
https://llvm.org/bugs/show_bug.cgi?id=28153


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273904 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed