Make sure we don't generate stubs for any of these functions because they

Make sure we don't generate stubs for any of these functions because they
don't exist in libc. This is really not the right way to solve this problem;
but it's not clear to me at this time exactly what is the right way.
If we create stubs here, they will cause link errors because these functions
do not exist in libc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189727 91177308-0d34-0410-b5e6-96231b3b80d8