Pass some things to the linker that gcc passes. -r is the only one of these that...

Pass some things to the linker that gcc passes.  -r is the only one of these that I'm sure about, but the others seem to be listed on FreeBSD by gcc -dumpspecs, so I hope they're right.  Apparently -r is also not passed on GNU/Linux (and should be), but I can't see where the toolchain definition for this platform live.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111114 91177308-0d34-0410-b5e6-96231b3b80d8