Skip tests that segfault or are inconsistent on FreeBSD

I now see no unexpected failures on FreeBSD on a local run of the test
suite.

llvm.org/pr17214
llvm.org/pr17225
llvm.org/pr17231
llvm.org/pr17232
llvm.org/pr17233



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@190709 91177308-0d34-0410-b5e6-96231b3b80d8