Driver: Allow Render{Separate,Joined} option flags on JoinedOrSeparate option types.

Also, simplify/fix SeparateArg::render with forced join.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99022 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed