IR: Change clang to set -preserve-bc-uselistorder

Change `clang` to set `-preserve-bc-uselistorder` for the driver options
`-emit-llvm` and `-save-temps`.  The former is useful for reproducing
results from `clang` in `opt` or `llc`, while the latter prevents
`-save-temps` from affecting the output.  This is part of PR5680.

`-preserve-bc-uselistorder=true` is currently on by default, but a
follow-up commit in LLVM will reverse it.

llvm-svn: 234920