Re-enable TestRegisters and TestTargetWatchAddress on Linux
- TestRegisters passes locally (llvm.org/pr16301 no longer reproduces) -- verifying this on buildbots
- TestTargetWatchAddress also passes locally, and referenced llvm.org/pr14323 which is now closed



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@190104 91177308-0d34-0410-b5e6-96231b3b80d8