[WinEH] Remove calculateCatchReturnSuccessorColors

The functionality that calculateCatchReturnSuccessorColors provides was
once non-trivial: it was a computation layered on top of funclet
coloring.

These days, LLVM IR directly encodes what
calculateCatchReturnSuccessorColors computed, obsoleting the need for
it.

No functionality change is intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256965 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed