Fix up TestRegisters for Linux ptracer lock-down.

All of these test fixups are prep work for when llgs is
running with llgs for local process debugging, where these
tests fail without the ptracer lock-down suppression.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@220656 91177308-0d34-0410-b5e6-96231b3b80d8