Added the ability to StackFrame::GetValueForVariableExpressionPath(...) to avoid

fragile ivars if requested. This was done by changing the previous second parameter
to an options bitfield that can be populated by logical OR'ing the new 
StackFrame::ExpressionPathOption enum values together:

    typedef enum ExpressionPathOption
    {
        eExpressionPathOptionCheckPtrVsMember   = (1u << 0),
        eExpressionPathOptionsNoFragileObjcIvar = (1u << 1),
    };

So the old function was:
     lldb::ValueObjectSP
     StackFrame::GetValueForVariableExpressionPath (const char *var_expr, bool check_ptr_vs_member, Error &error);

But it is now:

    lldb::ValueObjectSP
    StackFrame::GetValueForVariableExpressionPath (const char *var_expr, uint32_t options, Error &error);

This allows the expression parser in Target::EvaluateExpression(...) to avoid
using simple frame variable expression paths when evaluating something that might
be a fragile ivar.

llvm-svn: 123938