Fixed "log enable linux registers" and added a test.
- Eliminated the use of static for methods that read m_register_infos, so that these routines can be implemented in the base class.
- Eliminated m_register_infos in the base class because this is not used when derived classes call UpdateRegisterInfo.
- Also moved the namespace using declarations from headers to source files.

Thanks to Daniel and Samuel for their review feedback.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181538 91177308-0d34-0410-b5e6-96231b3b80d8