Fix CLI commands in lldb-mi.

This patch fixes execution of CLI commands in MI mode. The CLI commands are 
executed using "-interpreter-exec" command. The bug was in the 
CMICmnLLDBDebugSessionInfo class which contained the following members: 
SBProcess, SBTarget, SBDebugger and SBListener, but CLI commands don't affect
them and they aren't updated. Therefore some members can contain incorrect 
(or obsolete) reference and it can cause an error. My patch removes these 
members and uses getters that provides the updated instance every time it is used.

Patch from Ilia K ki.stfu@gmail.com. Approved by Greg.

llvm-svn: 227958