Add expectedFailureFreeBSD test wrapper


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187069 91177308-0d34-0410-b5e6-96231b3b80d8
test_iter_registers is expected to fail on FreeBSD

Added comment to llvm.org/pr14600 that it fails on FreeBSD in the same way
as Linux.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187070 91177308-0d34-0410-b5e6-96231b3b80d8