Fixed the implementation of "bool Block::Contains (const Block *block) const"

to return the correct result.

Fixed "bool Variable::IsInScope (StackFrame *frame)" to return the correct
result when there are no location lists.

Modified the "frame variable" command such that:
- if no arguments are given (dump all frame variables), then we only show
  variables that are currently in scope
- if some arguments are given, we show an error if the variable is out of 
  scope

llvm-svn: 113830